Update playbooks_roles.rst

Fixes https://github.com/ansible/ansible/issues/7241
Removing hard coded link and replacing with reference
Fix the synopsis in ansible-pull man page.
Update playbooks_variables.rst

There is some kind of duplicated content with http://docs.ansible.com/faq.html#how-do-i-loop-over-a-list-of-hosts-in-a-group-inside-of-a-template and this gotcha isn't listed here.
Update developing_modules.rst
Updating Role class for new DataLoader stuff
Ignore compiled Python for documentation.

When running `ansible-doc --list` a lot of errors are
generated when `ansible-doc` tries to find documentation
strings in `.pyc` files.
Update playbooks_intro.rst

Small punctuation/grammar fix.
Merge pull request #9402 from mscherer/fix_man_ansible_pull

Fix the synopsis in ansible-pull man page.
Merge pull request #9410 from dannyroberts/patch-1

Update developing_modules.rst
Merge pull request #9422 from tonk/docfix

Ignore compiled Python for documentation.
Merge pull request #9425 from bobobox/patch-1

Typo fix in playbooks_intro.rst
Merge pull request #9216 from nmadhok/patch-3

Update playbooks_roles.rst
More v2 roles class work

* added ability to set parents (will be used when the deps are loaded)
* added role caching, so roles are not reloaded needlessly (and for
  use in detecting when roles have already been run)
* reworked the way metadata was stored - now individual attribute fields
  instead of a dictionary blob
Adding role deps to v2 Role class and fixing some bugs
added fact caching hint
Add a changelog entry for how the git module has changed.
Pull in git submodule tracking
Add branch info for our submodules
Test the git changes for the git module's recursive flag