resolve: update commands.resolve.confirm help text

Included --mark and --unmark in the help text of
resolve.confirm.config.

Differential Revision: https://phab.mercurial-scm.org/D4103

mercurial/help/config.txt

@@ -439,8 +439,7 b' effect and style see :hg:`help color`.'
 ------------
 
 ``resolve.confirm``
-    Confirm before re-merging all unresolved files when running
-    :hg:`resolve --all`.
+    Confirm before performing action if no filename is passed.
     (default: False)
 
 ``resolve.mark-check``