Signed-off-by: NAndrea Frittoli <andrea.frittoli@gmail.com>

Add instruction in Dockerfile to declare the /src folder a trusted Git
directory.

Docsy now has versioned releases and uses Hugo modules (a wraper around
Go modules), this PR update the website to be compatible with the latest
version of Docsy.

- Create go.mod and go.sum files for compatibility with Hugo modules.
- Delete checked in theme and dependencies.
- Update base layout for compatibility with latest theme.
- Update packaje.json to match required dependencies and replace legacy
  values

Dibyo has reviewed multiple PRs for this repo. It would be very helpful
having him as OWNER to approve PRs.

Based on feedback, this commit:

-  Explicitly mention in the installation instructions that `tkn` is the
   command name of the Tekton CLI.

-  Provide a better description of when the installation of Tekton
   Pipelines is complete. Namely, when both tekton-pipelines-controller
   and tekton-pipelines-webhook are `READY`.

-  Consistent capitalization of "Task", "TaskRun", "Pipeline",
   "PipelineRun", "Workspace", and "Step". Since these are first class
   objects with a specific meaning meaning within Tekton, we treat them
   as nouns when writing docs.

Fix typographical errors in the code samples.

Updating the Deployment image from Ubuntu Xenial to Ubuntu Foca requires
using a newer version of Python.

Correct mis-typed name of desired `pipelineRef`.

Signed-off-by: NAndrea Frittoli <andrea.frittoli@gmail.com>

A tutorial that shows how to create a Tekton Pipeline to build and push
an image with Kaniko.

Create a new section for how-to's. This section will include end-to-end
guides for common tasks. The first one is how to create a Pipeline to
clone a repository.

Add the docs for triggers v0.20.0

Add most recent release `v0.26.x` and `main` as the only options for
now as we've updated the structure and links to ensure they work
correctly on both GitHub and the website.

References to the Katacoda scenarios have been removed
from the docs and website so we should also remove the content now.

Update the dev section as recommended by `netlify dev` to avoid
the framework selection prompt on startup. Without this the command
hangs waiting for user input. See output from netlify CLI that
suggested the change:

```
$ netlify dev
◈ Netlify Dev ◈
◈ Injected netlify.toml file env var: HUGO_VERSION
◈ Ignored general context env var: LANG (defined in process)
◈ Ignored general context env var: LC_ALL (defined in process)
? Multiple possible start commands found Hugo-hugo server -w
Add 'framework = "hugo"' to the [dev] section of your netlify.toml to avoid this selection prompt next time
◈ Starting Netlify Dev with Hugo
hugo server \
        --baseURL http://localhost:8888/ \
        --buildDrafts \
        --buildFuture \
        --disableFastRender \
        --ignoreCache \
        --watch
```

Remove `blackfriday` and use `goldstar` as default parser for hugo.

The blackfriday has been outdated and is giving rendering issues in some [cases](https://github.com/tektoncd/website/issues/323).
As it is also not being maintained, it better to switch to default markdown parser supported and encouraged by [hugo docs](https://gohugo.io/getting-started/configuration-markup/#configure-markup).

Using this the render issue for [interceptors](https://github.com/tektoncd/website/issues/323) was fixed

Include a series of introductory videos that can be very helpful for
many new users.

Add the docs for triggers v0.18.0 & v0.19.0, and updated v0.17.0 to v0.17.1

Closes https://github.com/tektoncd/website/issues/366

- [x] tekton.dev home page
	- [x] Get started with interactive tutorials' which links to https://tekton.dev/try/
		- Update the link text to: 'Get started with Tekton.'
		- Update the URL to point to our new tutorial: `https://tekton.dev/docs/getting-started/`
- [x] 'Try Tekton' block towards the bottom of the page which links to the Katacoda playground scenario
	- Update the text to: 'Learn, explore, and experiment with Tekton by following the tutorial.'
	- Make the word 'tutorial' a link with URL pointing at `https://tekton.dev/docs/getting-started/`
- [x] 'Try' link in the site header which also links to `https://tekton.dev/try/`
	- remove the link, page, and associated content

Since we're removing the 'Try' page from the website, as well as
the associated Katacoda scenarios, remove the reference to this
from the end of the asciinema recording which is displayed on
the home page.

This commit makes some updates to the concepts informations:

- Update the navigation to keep the conceptual information under the
  "Concepts" section, including the main Overview.

- Delete references to deprecated PipelineResources.

- Update path for images to be absolute instead of relative. In some
  documents relative paths don't render correctly.

Updating the website configuration to include the two latest major releases.

Alpine containers don't have bash, so need to change the first line.

Introductory guide for newcomers. This is a two-file quickstart that
shows a simple example to create a task and a pipeline.

These tutorials do not include new information. The information here is
reorganized to be easier to understand for newcomers. Including
prescritpive steps that the user just has to copy/paste .

Currently the netlify deploy uses hugo v0.53, which is almost 4 years
old and has some big inconsistencies when rendering markdown. This bumps
hugo up to the latest release.