Removing extra blank lines in docs that serve
no purpose, as well as some --- lines that also
are not needed.

Previously, we used brackets to denote the tier badges,
but this made Kramdown, the docs site Markdown renderer,
show many warnings when building the site. This is now
fixed by using parentheses instead of square brackets.

This was caused by [PREMIUM] looking like a link to
Kramdown, which couldn't find a URL there.

See:
- https://gitlab.com/gitlab-com/gitlab-docs/merge_requests/484
- https://gitlab.com/gitlab-org/gitlab-ce/issues/63800

Update index.md.... add instructions on how to add a `values.yaml` override file to the default auto-deploy-app helm chart by setting `HELM_UPGRADE_EXTRA_ARGS` to `--values my-values.yaml` (or `-f my-values.yaml`).

This will make it more obvious to anyone looking to customize these
files what the source code actually is.

The previous examples did work however they had a problem when the
bin/setup script installed a different bundler version than the one in
your Gemfile.lock.  It is safer to use `/bin/herokuish procfile exec` to
get access to all the environment already installed for your application
instead of installing bundler again.

Update documentation to reflect removal

Part of https://gitlab.com/gitlab-org/gitlab-ce/issues/49520
(Covers helm charts; does not cover docker repos)

Also note that apps will be released into the Kubernetes namespace for
the environment, and that GitLab < 11.4 used a dedicated Tiller

Update these sections to reflect Kubernetes resources
now being created as a build prerequisite. Remove section
about deploys not being triggered as it is no longer accurate.

Includes a new section on our Auto Devops documentation about enabling
or disabling Auto DevOps at group level.

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/58810

We were emphasising a point that's no longer true since we implemented
deploy tokens in 11.0 so rationalize the docs here.