[3.6] bpo-30380: Fix Sphinx 1.6.1 warnings. (GH-1613) (#1614)

* Use explicit numbering for footnotes referred by explicit number.
* Restore missed footnote reference in stdtypes.rst.
* Fix literal strings formatting in howto/urllib2.rst.
* Update susp-ignored.csv for zipapp.rst.
* Fix suspicious mark up in Misc/NEWS..
(cherry picked from commit d97b7dc94b19063f0589d401bdc4aaadc7030762)
diff --git a/Doc/library/xml.etree.elementtree.rst b/Doc/library/xml.etree.elementtree.rst
index b54eace..7d814ad 100644
--- a/Doc/library/xml.etree.elementtree.rst
+++ b/Doc/library/xml.etree.elementtree.rst
@@ -1192,7 +1192,7 @@
 
 .. rubric:: Footnotes
 
-.. [#] The encoding string included in XML output should conform to the
+.. [1] The encoding string included in XML output should conform to the
    appropriate standards.  For example, "UTF-8" is valid, but "UTF8" is
    not.  See https://www.w3.org/TR/2006/REC-xml11-20060816/#NT-EncodingDecl
    and https://www.iana.org/assignments/character-sets/character-sets.xhtml.