- Show Knative install button on group/instance cluster pages
- Allow Knative to be installed on group/instance clusters
- Add feature specs for installing applications on group/instance
  clusters
- Add changelog entry
- Update docs to reflect that Knative can now be installed on
  group-level and instance-level clusters

Since 5142bd73, we are using the official chart now.

Signed-off-by: NBalasankar "Balu" C <balasankar@gitlab.com>

Our current version of Cert-Manager does not uninstall
cleanly, and we must manually remove custom resource
definitions.

Also creates specs

Only allow Helm to be uninstalled if it's the only app

- Remove Tiller leftovers after reser command
- Fixes specs and offenses

Adds changelog file

Fix reset_command specs

- After uninstalling the knative helm chart it's necessary to also
remove some leftover resources to allow the cluster to be clean
and knative to be reinstalleable.
- Adds knative uninstall disclaimer
- Uninstall ksvc before uninstalling knative

Make list of Knative and Ingres resources explicit

- To avoid deleting unwanted resources we are listing exact
which resources will be deleted rather than simply deleting any
resource that contains istio or knative words.

Also fixes links to section headings that
have changed.

Correct the spacing of unordered markdown lists
in docs, to maintain standards of documentation,
in /user and others.

- Set as uninstallable app
- Update docs
- Adjust specs

Add backticks around square brackets, or fix links, as necessary.