Make RM duty clearer.

"recently" is too vague IMO for something that's to be done yearly.
No need to justify why exactly this has to be done, focus on the need action.

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

@@ -64,11 +64,9 @@ the best place to track such tickets.
 
 ## At least for the first release of the year
 
-We use a `@doc` cucumber tag to ensure to test only scenarios related to
-the shipped Tails documentation for the documentation branches. Once in
-a while (at least yearly), the RM should have a look at recently added
-scenarios or features and check if the ones that depend on the
-documentation have this tag.
+Have a look at scenarios or features added or modified since last time
+this check was done, and check if the ones that depend on the
+documentation have the `@doc` tag.
 
 ## Make the release happen