Add contributing guidelines document

[jGaboardi]

Add contributing guidelines document

[jGaboardi]

xref: #44 (comment)

Should our contributing guidelines:

• (a) go in the README.md
• (b) go in a CONTRIBUTING.md
• (c) go in both
• (d) go somewhere else?

I think probably (c), but what's yall's thoughts @anastassiavybornova @martinfleis ?

[martinfleis]

B.

[martinfleis]

I have two reasons for that. One is that I see ReadMe and contributing guide as document for different audience, where Readme is part of the user-facing documentation (hence no A). And second is that I dislike having the same information at two places at the same time as they will inevitably get out of sync in time (hence no C).

[anastassiavybornova]

Agree with (b)! (and it will be linked in the README so no need for (c) )