Update configuration screenshots for Slack and Mattermost
Update list of events for Mattermost

Add "read more" line to pod logs

Fix bad link to pod logs

This feature was introduced in 12.0, not in 11.11.

Not my initial idea but when I write the issue I see this field is wrong

Add `Variable Types` section to explain supported variable types and
update example and related screenshots.

When this option is enabled, GitLab will create namespaces and service
accounts as usual. When disabled, GitLab wont create any project
specific kubernetes resources

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/56557

Reporters can manage labels; you don't need to be a Developer.

This backports API and quick action docs.

The original issue didn't specify this, but the code always allowed
reporters to do everything here. I think that's correct because

1. Developer permissions normally refer to code, and boards are to do
   with issues.
2. Reporters can manage epics, as well as labels on
   issues, which are in a similar space.