Refactored the Pipelines navigation. (#820)

* Refactored the Pipelines navigation.

* Added redirects.

* Fixed typo GPC

content/_redirects

@@ -25,15 +25,24 @@
 /docs/pipelines/pipelines-ui/	         /docs/pipelines/pipelines-quickstart/
 
 # Restructured the pipelines docs.
-/docs/pipelines/output-viewer/                 /docs/pipelines/metrics/output-viewer/
-/docs/pipelines/pipelines-metrics/             /docs/pipelines/metrics/pipelines-metrics/
+/docs/pipelines/output-viewer/                 /docs/pipelines/sdk/output-viewer/
+/docs/pipelines/pipelines-metrics/             /docs/pipelines/sdk/pipelines-metrics/
 /docs/pipelines/build-component/               /docs/pipelines/sdk/build-component/
-/docs/pipelines/enable-gpu-and-tpu/            /docs/pipelines/sdk/enable-gpu-and-tpu/
+/docs/pipelines/enable-gpu-and-tpu/            /docs/pipelines/sdk/gcp/enable-gpu-and-tpu/
 /docs/pipelines/install-sdk/                   /docs/pipelines/sdk/install-sdk/
 /docs/pipelines/lightweight-python-components/ /docs/pipelines/sdk/lightweight-python-components/
 /docs/pipelines/build-pipeline/                /docs/pipelines/tutorials/build-pipeline/
 /docs/pipelines/pipelines-tutorial/            /docs/pipelines/tutorials/pipelines-tutorial/
 
+/docs/pipelines/metrics/                       /docs/pipelines/sdk/pipelines-metrics/
+/docs/pipelines/metrics/pipelines-metrics/     /docs/pipelines/sdk/pipelines-metrics/
+/docs/pipelines/metrics/output-viewer/         /docs/pipelines/sdk/output-viewer/
+/docs/pipelines/concepts/*                     /docs/pipelines/overview/concepts/:splat
+/docs/pipelines/pipelines-overview/            /docs/pipelines/overview/pipelines-overview/
+/docs/pipelines/sdk/enable-gpu-and-tpu/        /docs/pipelines/sdk/gcp/enable-gpu-and-tpu/
+/docs/pipelines/preemptible/                   /docs/pipelines/sdk/gcp/preemptible/
+/docs/pipelines/reusable-components/           /docs/pipelines/sdk/reusable-components/
+
 # Moved the guide to monitoring GKE deployments.
 /docs/other-guides/monitoring/                 /docs/gke/monitoring/
 

content/docs/pipelines/metrics/_index.md

-+++
-title = "Metadata and Metrics"
-description = "Using metadata and metrics in Kubeflow Pipelines"
-weight = 60
-+++
\ No newline at end of file

content/docs/pipelines/overview/_index.md

++++
+title = "Understanding Pipelines"
+description = "Overview and concepts in Kubelow Pipelines"
+weight = 20
++++
\ No newline at end of file

content/docs/pipelines/concepts/_index.md → content/docs/pipelines/overview/concepts/_index.md

 +++
 title = "Concepts"
 description = "Understand the terminology used in Kubeflow Pipelines"
-weight = 30
+weight = 40
 +++
\ No newline at end of file

content/docs/pipelines/pipelines-overview.md → content/docs/pipelines/overview/pipelines-overview.md

 +++
 title = "Overview of Kubeflow Pipelines"
-description = "Overview of Kubeflow Pipelines"
+description = "Understanding the goals and main concepts of Kubeflow Pipelines"
 weight = 10
 +++
 

content/docs/pipelines/pipelines-quickstart.md

 +++
 title = "Pipelines Quickstart"
 description = "Getting started with Kubeflow Pipelines"
-weight = 20
+weight = 10
 +++
 
 Use this guide if you want to get a simple pipeline running quickly in

content/docs/pipelines/reference/_index.md

 +++
 title = "Reference"
 description = "Reference docs for Kubeflow Pipelines"
-weight = 55
+weight = 70
 +++

content/docs/pipelines/sdk/_index.md

 +++
 title = "Building Pipelines with the SDK"
 description = "Use the Kubeflow Pipelines SDK to build components and pipelines"
-weight = 50
+weight = 30
 +++
\ No newline at end of file

content/docs/pipelines/sdk/best-practices.md

 +++
 title = "Best Practices for Designing Components"
 description = "Designing and writing components for Kubeflow Pipelines"
-weight = 10
+weight = 60
 +++
 
 This page describes some recommended practices for designing

content/docs/pipelines/sdk/build-component.md

 +++
 title = "Build Components and Pipelines"
 description = "Building your own component and adding it to a pipeline"
-weight = 3
+weight = 30
 +++
 
 This page describes how to create a component for Kubeflow Pipelines and how

content/docs/pipelines/sdk/component-development.md

 +++
 title = "Build Reusable Components"
 description = "A detailed tutorial on creating components that you can use in various pipelines"
-weight = 3
+weight = 40
 +++
 
 This page describes how to author a reusable component that you can

content/docs/pipelines/sdk/dsl-recursion.md

 +++
 title = "DSL Recursion"
 description = "Author a recursive function in DSL"
-weight = 50
+weight = 110
 +++
 
 This page describes how to write recursive functions in the domain specific language (DSL) provided by the Kubeflow Pipelines SDK.

content/docs/pipelines/sdk/gcp/_index.md

++++
+title = "GCP-specific Uses of the SDK"
+description = "SDK features that are available on Google Cloud Platform (GCP) only"
+weight = 130
++++
\ No newline at end of file

content/docs/pipelines/sdk/enable-gpu-and-tpu.md → content/docs/pipelines/sdk/gcp/enable-gpu-and-tpu.md

 +++ 
 title = "Enable GPU and TPU"
 description = "Enable GPU and TPU for Kubeflow Pipelines on Google Kubernetes Engine"
-weight = 30
+weight = 10
 +++
 
 This page describes how to enable GPU or TPU for the pipeline on GKE by using the Pipelines 

content/docs/pipelines/preemptible.md → content/docs/pipelines/sdk/gcp/preemptible.md

 +++
 title = "Using Preemptible VMs and GPUs on GCP"
 description = "Configuring preemptible VMs and GPUs for Kubeflow Pipelines on GCP"
-weight = 65
+weight = 10
 +++
 
 This document describes how to configure preemptible virtual machines

content/docs/pipelines/sdk/install-sdk.md

 +++
 title = "Install the Kubeflow Pipelines SDK"
 description = "Setting up your Kubeflow Pipelines development environment"
-weight = 1
+weight = 20
 +++
 
 This guide tells you how to install the 

content/docs/pipelines/sdk/lightweight-python-components.md

 +++
 title = "Build Lightweight Python Components"
 description = "Building your own lightweight pipelines components from Python"
-weight = 4
+weight = 50
 +++
 
 Lightweight Python components do not require you to build a new container image

content/docs/pipelines/metrics/output-viewer.md → content/docs/pipelines/sdk/output-viewer.md

 +++
 title = "Visualize Results in the Pipelines UI"
 description = "Visualizing the results of your pipelines component"
-weight = 8
+weight = 80
 +++
 
 This page shows you how to use the Kubeflow Pipelines UI to visualize output 

content/docs/pipelines/sdk/parameters.md

 +++
 title = "Pipeline Parameters"
 description = "Passing data between pipeline components"
-weight = 35
+weight = 70
 +++
 
 The [`kfp.dsl.PipelineParam` 

content/docs/pipelines/metrics/pipelines-metrics.md → content/docs/pipelines/sdk/pipelines-metrics.md

 +++
 title = "Pipeline Metrics"
 description = "Export and visualize pipeline metrics"
-weight = 9
+weight = 90
 +++
 
 This page shows you how to export metrics from a Kubeflow Pipelines component. 

content/docs/pipelines/reusable-components.md → content/docs/pipelines/sdk/reusable-components.md

 +++
 title = "Index of Reusable Components"
 description = "A list of Kubeflow Pipelines components that you can use in your pipelines"
-weight = 60
+weight = 120
 +++
 
 A Kubeflow Pipelines *component* is a self-contained set of code that performs 

content/docs/pipelines/sdk/sdk-overview.md

 +++
 title = "Introduction to the Pipelines SDK"
 description = "Overview of using the SDK to build components and pipelines"
-weight = 2
+weight = 10
 +++
 
 The [Kubeflow Pipelines 

content/docs/pipelines/sdk/static-type-checking.md

 +++
 title = "DSL Static Type Checking"
 description = "Statically check the component I/O types"
-weight = 40
+weight = 100
 +++
 
 This page describes how to integrate the type information in the pipeline and utilize the 

content/docs/pipelines/tutorials/_index.md

 +++
 title = "Samples and Tutorials"
 description = "Try the samples and follow detailed tutorials for Kubeflow Pipelines"
-weight = 40
+weight = 60
 +++
\ No newline at end of file

content/docs/pipelines/upgrade.md

 +++
 title = "Upgrading and Reinstalling"
 description = "How to upgrade or reinstall your Kubeflow Pipelines deployment"
-weight = 70
+weight = 50
 +++
 
 Starting from Kubeflow version 0.5, Kubeflow Pipelines persists the