adding some links to readmine for better discoverability of content/contact methods that help people to migrate. 
related issue is: tails/tails#17722

The original link became a 404 after a GitLab upgrade, which was
a problem. 2a2089c5 fixed the 404,
although by making the link point to a different page than intended.

The previous link was broken for at least 2 different reasons.

While I'm at it:

 - switch this link to using the tails_gitlab ikiwiki shortcut
 - make the URL filter the labels it's about

Previously it linked to Starter issues in the tails/tails project,
but we have a few Starter issues in other tails/* projects.

Somehow I managed to mistype the name of the Starter label.

Let's link to the code that resulted from resolving these issues.

That was fixed years ago.

Fixes regression introduced in ca006f09.