Docs feedback: GitLab Runner upgrade/update instructions could be better

In the instructions for updating GitLab Runner for Windows, readers are linked to the bleading edge download instructions. This would be better replaced by a page that explains the GitLab Runner releases because the "bleading edge" only links to the latest releases.

Similarly for all other Runner platforms, their update/upgrade instructions have problems

• inconsistent use of "upgrade" or "update" to mean "get a newer version of GitLab Runner"
• Windows seems to be less supported than it actually is
• Some pages mention runner release tags, others don't, none actually links to where the tags are (except for Bleading Edge, ironically).

This issue is to track making changes across the install and upgrade pages for GitLab Runner to address this problem