Suggestion: Document best practices and references for contributors

[DimitriPapadopoulos]

It would be beneficial to create a list of suggestions and best practices for contributors, drawing from advice provided by maintainers in previous issues and pull requests. The recommendations could include:

• Use the OED (Oxford English Dictionary) as the primary reference for English word spellings.
• Use SCOWL and Friends as the open-source English dictionary of reference for spell checkers. Let it have the last word.
• Utilize the Google Ngram Viewer to check the frequency and commonality of terms or proposed corrections.
• When adding dictionary entries, always include all verbal forms (e.g., present, past, participle) and both singular and plural nouns.

A point for discussion: Should this advice be added to the main README.rst, understanding that it could clutter the file, or should we create and use a project wiki page to keep the README concise?

Feedback and preferences from maintainers and contributors on the above structure would be appreciated.

Based on #3849 (comment).

[nathanjmcdougall]

Maybe consider a CONTRIBUTING.md file for detailed contributing instructions, pulling it out of the README.