* inventory plugin docs
* added set options
* minor wording and formatting fixes
* changed headers to std as per #35520, also added to main readme
* unified inventory plugin devel, referenced from generic plugin dev
* fixed typos and update as per feedback
* developing_modules.rst is now in dev_guide, sync changes and delete the old version
* Cleaner RST & formatted code
* Tidyup roadmaps
* Link to repomerge
* Pull in abadger's fixes From https://github.com/ansible/ansible/compare/docs-code-block-fixes?expand=1
* Clean docsite/rst (apart from ROADMAP