GitLab: link to lists of labels

wiki/src/contribute/working_together/GitLab.mdwn

@@ -162,12 +162,20 @@ Every open issue must have exactly 0 or 1 of these labels:
  - _P:High_
  - _P:Urgent_
 
+See the
+[[!tails_gitlab groups/tails/-/labels?search=P%3A
+desc="list of priority labels"]].
+
 ## Category
 
 We classify issues with labels whose name starts with _C:_.
 
 For example, _C:Email Client_ or _C:Installation_.
 
+See the
+[[!tails_gitlab groups/tails/-/labels?search=C%3A
+desc="list of category labels"]].
+
 ## Type of work
 
 To indicate the type of work that's needed to complete the next step
@@ -184,6 +192,10 @@ For example:
    people to do, outside of Tails
  - _T:Website_: website work not covered by other options
 
+See the
+[[!tails_gitlab groups/tails/-/labels?search=T%3A
+desc="list of type of work labels"]].
+
 ## Other labels
 
  - _Starter_: issues flagged as *Starter* can be a good pick for new contributors