[1.6.x] Fixed typo in storage docs

Backport of 82f466b571 from master
[1.6.x] Fixed #21747 -- Added {% elif %} to template topics guide.

Thanks gcc for the suggestion.

Backport of 9e5033b302 from master
[1.6.x] Fixed #21727 -- Added some links to help clarify topics/auth/default.txt

Thanks daGrevis for the suggestion.

Backport of d35f2bfd5b from master
[1.6.x] Fixed #21768 -- Corrected TemplateView context section.

Thanks nedbatchelder for the report and claudep for the patch.

Backport of c05b2f58e7 from master
[1.6.x] Fixed #18285 -- Documented that bulk_create doesn't work with M2M relationships.

Backport of 9173d2cb74 from master
[1.6.x] Fixed #20052 -- Discouraged use of Jython given the current state of django-jython.

Thanks Josh Juneau (maintainer of django-jython) for the review.

Backport of a67e327db5 from master
[1.6.x] Fixed #13116 -- Described scope of variables created by {% url ... as var %} syntax.

Thanks leif_p for the suggestion.

Backport of 4a5aac47a6 from master
[1.6.x] Fixed #18942 -- Clarified usage of {% get_static_prefix %}.

Thanks Aymeric for the suggestion.

Backport of bc7668eb51 from master
[1.6.x] Added a note about LTS releases.

Backport of a44cbca2a5f1388c6511dad48443877fa660845a from master.
[1.6.x] Fixed #21834 -- Clarifed usage of template_name in tutorial part 4.

refs #21195 on master.
[1.6.x] Fixed #21726 -- Clarified that password should not be included in REQUIRED_FIELDS.

Thanks russellm for the report.

Backport of 6f06c749b7 from master
[1.6.x] Fixed #21529 -- Noted that {% url %} encodes its output (refs #13260).

Backport of dfc092622e from master
[1.6.x] Added a link to the 1.6 release notes which also fixed a rendering issue.

Backport of 2171341162 from master
[1.6.x] Fixed #20834 -- Described how caching of user permissions works.

Thanks Giggaflop and Jennifer Casavantes.

Backport of 5f9790072d from master
[1.6.x] Don't show `self` in the list of arguments of a method.

This is consistent with Python's official documentation
and it's a sphinx recommendation too[1].

[1] http://sphinx-doc.org/markup/desc.html#dir-method

Refs #21855.

Backport of 79e1d6ebd70898d514a44b85648e3d24104c4243 from master.
[1.6.x] Always use parentheses when documenting a method with no arguments.

Backport of 05d36dc06e6d767bb28993c65a54b703f319a386 from master.
[1.6.x] Fixed some punctuation; thanks Chris Jerdonek.

Backport of 81830ce34f from master
[1.6.x] Fixed #21787 -- regression in MTI .exclude() queries

Backpatch of 78a2617703bc1dada409f126db5c3db214913ff4 from master.
[1.6.x] Fixed #21824 -- Added reference to LTS in docs/internals/security.txt

Backport of 4d8209431d from master
[1.6.x] Fixed #21869 -- Fixed docs building with Sphinx 1.2.1.

Thanks tragiclifestories for the report.

Backport of e1d18b9d2e from master