Show help pages from GitLab instance (not docs.gitlab.com)

Description

In !1796 (merged), we introduced a Documentation link. This should link to the relevant GitLab instance's help page (not docs.gitlab.com). This might be an unsolved problem in the VSCode extension 🤔

Context

The following discussion from !1796 (merged) should be addressed:

• @pslaughter started a discussion:

  issue (non-blocking): To fully support self-managed instances that are airgapped (not able to reach out to the internet), we'll want to use the relevant help page from the GitLab instance instead of hardcoding this:

  • https://docs.gitlab.com/ee/development/documentation/help.html#linking-to-help

  I don't think we need to worry about this complexity here, but it's something we should try to solve in a follow-up. WDYT?