Release process: document bulk-edits for Redmine (Closes: #16588)

wiki/src/contribute/release_process.mdwn

@@ -1316,8 +1316,15 @@ tracker. For a list of candidates, see:
 * the "Fix committed" section on the *Release Manager View for ${VERSION:?}*
   in Redmine.
 
+Select these issues with the checkboxes in the first column, then
+right click on the list to display the context menu, and finally
+change the _Status_ there. Relationships between tickets will likely
+prevent you from closing all these issues at once, but at least
+you can process them in several smaller batches instead of one by one.
+
 Postpone to next release any remaining open issue for the version
-you've just released.
+you've just released. Use the right-click contextual menu to do so in
+one single batch.
 
 Then, mark the just-released Redmine milestone as done: go to the
 target version page, click *Edit*, and set *Status* to *Closed*.