To avoid having to delete and reapply a Pipelinerun when developing your
code, this PR switches to `generateName`, which adds a suffix to have a
unique name each time.

Additionally, this PR also fixes a problem with the latest version of
the `git-clone` Task in the Git clone tutorial.

Add the docs for Triggers v0.21.0

Commenting out the front matter allows to reuse that content in other
files where it may be relevant using the `readfile` shortcode. This
doesn't affect the normal functionality of the YAML front matter.

Recently, the git-clone task was updated to version 0.8 which is not
backwards compatible in that it is run as a non-root user which does not
have access to volumes mounted via workspaces by default. To accomodate
this change, the users need to update their PipelineRuns and TaskRuns
with `podTemplate.securityContext.fsGroup = 65532` to fix the
permissions on mounted volumes.

This commit makes this configuration change in the how-to guide.

Updating website sync configuration to include the latest
pipeline release - 0.39

Because Tekton imports content from several repos, this custom partial
ensures that the "edit" link points to the correct location.

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.