Tidy development environment documentation (#17215)
Summary of the issue:
The development environment documentation has a number of lint violations and inconsistencies.
Description of user facing changes
The development environment documentation has been slightly updated to be easier to read.
Description of development approach
- Fixed lint errors to do with headings and code blocks not being surrounded by blank lines.
- Slightly restructured dependency documentation so that submodules are organised into run time, build time and VS Code dependencies.
- Moved the reference to Doxygen to a new "Other dependencies" section.
- Fixed a couple of violations of the one-sentence-per-line rule.
- Changed in-text references to NV Access to use proper capitalisation and spacing ("NV Access" rather than "nvaccess" or a reference to our NVDA repo (`nvaccess/nvda`))
- Fixed some sentences not ending with full stops or colons.
- Changed the reference to WIL to call it "Windows Implementation Libraries (WIL)"
- Linked to the git submodules documentation.
