[docs] Add missing changes and links to Changelog

[Hundrec]

(fixes #3676) Oh whoops, was doing this at the same time as Eric

I've made a bunch of changes to the changelog that I think are necessary, so I'll be adding a commit to resolve merge conflicts with Eric's commit

All resolved!

Changes

• Add a few changes that are missing due to closed PRs
• Add PR links for new contributors in 0.5.2
• Add new contributors sections for 0.5.1, 0.5.0, 0.4.1, 0.4.0, and 0.3.3
• Add links to pull requests for all changes that came from a PR for all versions back to 0.3.3
• Tweak the spellings of some contributors' names to match their usernames on GitHub
• Various spelling and grammar fixes after 0.3.0
• Remove duplicate entries
• Fix a broken link in 0.4.1

And most of all...

• Change the 'h' in "2hot" to lowercase (and fixed M.I.L.F and DadBattle)