Thanks to everybody who contributed! We’re getting close to 500 people who have contributed comments or mathematics! Amazing!
The comments aren’t part of the Stacks project, so the discussion in the comments can be a bit more relaxed and loose than in the actual text; double checking your comment makes sense and can be parsed by others before you post is always a good idea.
I would appreciate people helping out, even and maybe especially, in small ways. Let me stress this: start with small things and see if you can get the maintainer (that’s me) to accept your contribution. For example, if you find a typo, then you can edit the latex file yourselves and send it in. The instructions are here. Just do one or a few typos at a time. You can add an omitted proof as a slightly larger project. Things that make it easier for me to accept contributions: (a) your edits use roughly the same coding style which you can easily deduce by looking around in the latex files, (b) the amount of detail given in a proof is roughly similar to what happens in nearby lemmas, and (c) you make a pull request on github (examples of pull requests).
Of course, if you find a mathematical error, I’d like to know immediately and in that case I encourage you to leave a comment on the website (so everybody can see what’s going on). It is very helpful if you precisely indicate where the error lies and thoughts you might have had on how to fix or work around the problem.