push.default doc: explain simple after upstream

As the "simple" mode is described in terms of what "upstream" does,
swap the order of these two entries so that the reader sees "upstream"
first and then reads "simple" with the knowledge of what "upstream"
does.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/config.txt

@@ -1689,14 +1689,14 @@ push.default::
   +
   This is currently the default, but Git 2.0 will change the default
   to `simple`.
-* `simple` - like `upstream`, but refuses to push if the upstream
-  branch's name is different from the local one. This is the safest
-  option and is well-suited for beginners. It will become the default
-  in Git 2.0.
 * `upstream` - push the current branch to its upstream branch.
   With this, `git push` will update the same remote ref as the one which
   is merged by `git pull`, making `push` and `pull` symmetrical.
   See "branch.<name>.merge" for how to configure the upstream branch.
+* `simple` - like `upstream`, but refuses to push if the upstream
+  branch's name is different from the local one. This is the safest
+  option and is well-suited for beginners. It will become the default
+  in Git 2.0.
 * `current` - push the current branch to a branch of the same name.
   +
   The `simple`, `current` and `upstream` modes are for those who want to