Add a gotcha section after trapped again.

README.maint

@@ -53,6 +53,18 @@ Release process:
   * Write an announcement.  Update https://savannah.gnu.org/projects/gnupg .
 
 
+Gotchas
+=======
+
+- If during "make distcheck" you get an error about a permission
+  problem moving foo.new.po to foo.po; this is caused by a check
+  whether the po files can be re-created.  Now if the first tarball
+  has been created in a different top directory and if there exists a
+  no distributed file with the string "GNU gnupg" (e.g. a log file
+  from running make) you end up with different comments in the po
+  files.  Check out /usr/lib/gettext/project-id for that silliness.
+
+