Now that the site has grown and gained in traffic, I feel like it could be updated to reflect the decisions which have been taken thanks to some meta questions asked these two last years.
I think that an update would help new comers to understand better what they can and can not ask or why their question was closed without having to dig the meta site.
It would also be helpful for our users handling the review queues to have an easily accessible compiled list of topics are allowed here.
I redacted an update for this section that I will post as a wiki answer to this question. My proposal contains 3 new paragraphs about questions that I feel like I often close, as well as links to the meta questions about these topics.
My writting in English is not always the best so it might need a bit of rewording by people more litterate than me and maybe it also lacks some topics I didn't think about. So as always on our site: let's discuss this update and make a decision!