Fixed versionadded and ordering of note in admin/index.txt

docs/ref/contrib/admin/index.txt

@@ -2174,18 +2174,18 @@ creating your own ``AdminSite`` instance (see below), and changing the
 Templates can override or extend base admin templates as described in
 `Overriding Admin Templates`_.
 
-.. versionadded:: 1.6
 .. attribute:: AdminSite.site_header
+.. versionadded:: 1.7
     The text to put at the top of each admin page, as an ``<h1>`` (a string).
     By default, this is "Django administration".
 
-.. versionadded:: 1.6
 .. attribute:: AdminSite.site_title
+.. versionadded:: 1.7
     The text to put at the end of each admin page's ``<title>`` (a string). By
     default, this is "Django site admin".
 
-.. versionadded:: 1.6
 .. attribute:: AdminSite.index_title
+.. versionadded:: 1.7
     The text to put at the top of the admin index page (a string). By default,
     this is "Site administration".