record: precise documentation

This patch improves the documentation of the recordfilter function to explain
that we need a translated string for the 'operation' argument.

mercurial/cmdutil.py

@@ -63,6 +63,7 b' def recordfilter(ui, originalhunks, oper'
     selected hunks.
     *operation* is used for ui purposes to indicate the user
     what kind of filtering they are doing: reverting, commiting, shelving, etc.
+    *operation* has to be a translated string.
     """
     usecurses =  ui.configbool('experimental', 'crecord', False)
     testfile = ui.config('experimental', 'crecordtest', None)