facts caching: fix missing json in jsonfile caching
Use "override" instead of "loaded second" to be clear about what happens

Need for clarification brought up here:
https://github.com/ansible/ansible/issues/9877
Merge pull request #9881 from resmo/fix/missing-json-jsonfile-caching

facts caching: fix missing json in jsonfile caching
Restore json import for redis as well.  Switch preference to simplejson for speed
Pull in apt changes
Update core modules for docker fix
Improve wording in playbooks_intro.rst

I was reading the docs and thought "that wording seems off."
Fix some typos in developing_modules.rst
Merge pull request #9908 from NateEag/patch-2

Improve wording in playbooks_intro.rst
Merge pull request #9910 from NateEag/patch-3

Fix some typos in developing_modules.rst