[3.12] gh-83505: Add markdown mimetype mapping (GH-17995)

[miss-islington]

(cherry picked from commit b6f0ab5)

Co-authored-by: Ryan Batchelder [email protected]

• Issue: Add mimetype for extension .md (markdown) #83505

[jaraco]

Since there was no objection from @Yhg1s, I'll make the executive decision to merge it. I'll be happy to revert it if requested.

[Yhg1s]

I can't object to a PR that wasn't brought to my attention, can I? :)

I don't actually think this is a good idea for 3.12, but I don't think it matters enough to revert the commit.

[jaraco]

I can't object to a PR that wasn't brought to my attention, can I? :)

I noticed that, but assumed (perhaps incorrectly) that tagging you on the parent issue was adequate notice. I could have been more careful about the notices.

I don't actually think this is a good idea for 3.12, but I don't think it matters enough to revert the commit.

It wasn't my intention to bully. Just say the word and I'll enact the revert.