Creating a new Reviewing PRs wiki page

[reticent-rem]

Correction/Clarification?

Summary

Saugia & roadrunner56 suggested in another PR comment thread that it could be valuable to add a wiki page around PR reviewing, so here it is!

mOctave wrote a superb set of tips for reviewers last year, so I've shamelessly linked it here and added a slightly condensed version to this doc. Definitely want any thoughts or tweaks since this is essentially those same tips.

[roadrunner56]

Thanks for doing this!
Perhaps you could link the StyleGoals page for when someone is reviewing a writing PR? Makes sense for a reviewer to know what the game's writing and grammar guidelines are.
Also, perhaps we should add something about how to review PRs on a basic, literal level - like 'go to the PR on GitHub, select "files changed", click on a line you want to make a suggestion for', etc. etc. because I know when I was starting out I didn't know any of that stuff. I think it would be helpful to people who aren't familiar with Github's UI.

[reticent-rem]

Great ideas, thanks! I added a tip bullet pointing to the style guide & wiki more generally, and linked resources for creating a Github account/reviewing your first PR. I think those suggestions will help first time contributors a lot with getting started!

[mOctave]

I haven't actually done any spelling or grammar checking on this (at least not yet), but I approve of my writing being used in this context.