chore: Update links to docs.gitlab.com

Description

As part of high-priority cleanup from gitlab-org/editor-extensions/gitlab.vim#139 (closed), time to check the CLI repo for any traces of docs.gitlab.com/ee/ — which went away after the Hugo migration.

I found a lot. 😞 Admittedly, many of the links still redirected properly, but let's fix them.

Some of this could have been caught if gitlab-vscode-extension#1934 had been implemented, but many of these were backend and required manual checks. booooo.

Related Issues

• Related to [VS Code] Add automated checking of external li... (gitlab-vscode-extension#1934)
• Related to Links in the Readme are not working (gitlab-org/editor-extensions/gitlab.vim#139 - closed)

How has this been tested?

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation
• Chore (Related to CI or Packaging to platforms)
• Test gap