Contributing guide - add link to CONTRIBUTING.md

[pfctdayelise]

It took me a while to realise the CONTRIBUTING.md had useful info not in the Contributing docs, so I've added a link between them. I imagine this doesn't need a separate issue or changelog callout but please correct me if wrong.

The checklist

• Associated issue
• A news fragment in the news/ directory to describe this fix with the extension .bugfix, .feature, .behavior, .doc. .vendor. or .trivial (this will appear in the release changelog). Use semantic line breaks and name the file after the issue number or the PR #.

[uranusjr]

Actually I wonder if it is a good idea to move (or at least copy) the development setup section into documentation, instead of linking to it… (I didn’t even know it exists)

[pfctdayelise]

It's not entirely clear to me what the difference between the two documents should be. So I could make the .md file just say "see (url)" and merge the content into the docs page?

[uranusjr]

CONTRIBUTING.md is essentially just a customary file to put these kind of information in. It also shows up (as a link) on the right hand side when you submit an issue or PR on GitHub. It would make more sense (IMO) to do this the other way around: add “see [link to documentation]” in CONTRIBUTING.md to point to the documentation.

[pfctdayelise]

Contributing.rst is the one that appears in the website. CONTRIBUTING.md is the one github links to. Which file are you proposing actually has the content?

[uranusjr]

The content should be in the rst one (in the documentation) IMO.

[pfctdayelise]

Hmm, pretty sure I mangled this by attempting to rebase. Let me make a clean attempt.