Apply paragraph description class on wp-admin/network.php for consistency.

props Hanni.
fixes #26264.
Built from https://develop.svn.wordpress.org/trunk@26405


git-svn-id: http://core.svn.wordpress.org/trunk@26305 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Rename mp6_color_scheme JS global to wp_color_scheme.

props kovshenin.
see #26263.
Built from https://develop.svn.wordpress.org/trunk@26406


git-svn-id: http://core.svn.wordpress.org/trunk@26306 1a063a9b-81f0-0310-95a4-ce76da25c4cd