Bup docsy version and comment out jinja2 code in vendor guidelines.

Some highlights about this new Docsy version:

- Better styles for tabs
- Improved readfile shortcode rendering
- Consistent code block styles

Community page with links to guidelines, communication channels and the
community repository.

Issues are created using the templates from tektoncd/.github,
the .github/issue_template.md file in this repo is for the
legacy template approach and no longer used.

Fixing a small typo which breaks the How-to Guide if followed blindly/copy-pasted.
The documentation refers to `pipeline,yaml` in line 49, but I believe it should be referring to `pipeline.yaml` ( using a punctuation instead of a comma ).

- Add contribution guidelines for platform specific docs
- Simplify existing contribution guidelines

This new section surfaces the installation documentation for all the
Tekton components.

This first iteration adds Pipelines and Triggers, more work is required
for other components docs to be included here.

- Add new beginners tutorial for Triggers.
- Modify Pipelines example to use one parameter.
- Make some editorial changes to the previous tutorials.

Docsy update v0.3.0 => v0.4.0

This PR updates the site and Docker configurations to run on an
environment closer to the Netlify production environment.

Move jquery back to header

Implement click-to-copy for code blocks. Code blocks with no syntax
highlight won't show the button

Additional changes:

- Bump up Popper and Bootstrap versions
- Move script-importing code from header to the scripts partial

Tekton Pipelines currently does not install on Kubernetes 1.25 due
to use of some deprecated resources that have been removed in that
release. Pin the version used for the `minikube start` command so
users following the tutorial have a working environment.

Signed-off-by: NVincent Demeester <vdemeest@redhat.com>

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.