[2.7] bpo-30380: Fix Sphinx 1.6.1 warnings. (GH-1613) (#1616)

* Use explicit numbering for footnotes referred by explicit number.
* Fix literal strings formatting in howto/urllib2.rst.
* Add `:noindex:` to duplicated definition of list.
* Update susp-ignored.csv for reference/expressions.rst.
(cherry picked from commit d97b7dc94b19063f0589d401bdc4aaadc7030762)
6 files changed