11.8 release

Merge on the 22nd at 14:30 UTC

> How to

During release

• Push the new version which will create a Docker image with the stable version.

  bundle exec rake "release:single[11.8]"

1. (Optional) If there are changes in the stable branches of the docs after the release version Docker image was created, rerun the release version pipeline.
2. Make sure the proper milestone is assigned to this MR and:
   1. Edit content/_data/versions.yaml and rotate the versions.
   2. Edit content/404.html and add the old removed version to the list of redirects at the bottom of the file.
   3. Edit dockerfiles/Dockerfile.archives and add the new version.
   4. Edit Dockerfile.master and rotate the versions.

Before merge

On the 22nd, a few minutes before merging this and before the scheduled pipeline runs:

1. Bump the versions in content/_data/versions.yaml for all online versions by pushing the change to the according stable branches.
2. Now it's time to merge.

After merge

1. Manually run the scheduled pipeline.