FT: link to unassigned MRs

As per today's team meeting.

wiki/src/contribute/working_together/roles/foundations_team.mdwn

@@ -25,7 +25,10 @@ The Tails Foundations Team is responsible for:
   in a timely manner (1 week in general, up to 2 weeks if needed in exceptional
   cases). If nobody on the Foundations Team can take care of a given MR,
   it's the Foundations Team's responsibility to ask for help:
-  - [[!tails_gitlab groups/tails/-/merge_requests desc="Merge Requests (MRs)"]]
+  - [[!tails_gitlab groups/tails/-/merge_requests desc="Merge Requests (MRs)"]],
+    and in particular
+    [[!tails_gitlab groups/tails/-/merge_requests?scope=all&utf8=✓&state=opened&assignee_id=None
+    desc="unassigned Merge Requests (MRs)"]]
   - [[!tails_gitlab groups/tails/-/issues?scope=all&utf8=%E2%9C%93&state=opened&label_name%5B%5D=Needs%20Validation
     desc="issues with the _Needs Validation_ label"]]