Add rst pages for new modjk state/module

This commit tells sphinx to build doc pages for these new files, and
adds them to the table of contents.
Cleanup docstrings in modjk state/module

Fixed spelling/grammar errors, improved formatting, and introduced links
to improve doc navigation.
Merge pull request #6674 from terminalmage/docs

Add docs for new modjk state/module
Merge branch 'develop' of github.com:saltstack/salt into hotfix/modjk-formatting