Merge branch 'jc/mention-tracking-for-pull-default'

We stopped mentioning `tracking` is a deprecated but supported
synonym for `upstream` in pull.default even though we have no
intention of removing the support for it.

* jc/mention-tracking-for-pull-default:
  doc: mention tracking for pull.default

Documentation/config.txt

@@ -1811,7 +1811,8 @@ push.default::
   +
   This is currently the default, but Git 2.0 will change the default
   to `simple`.
-* `upstream` - push the current branch to its upstream branch.
+* `upstream` - push the current branch to its upstream branch
+  (`tracking` is a deprecated synonym for this).
   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.