Cleanup on README.md

[lambdadog]

You mentioned in #369 that the README could use some love, so I've done my best to clean it up a bit.

Preview of the new README.md

This consists of, largely:

• Replacing dead links and updating ones which redirect or are now at a new location
  • Pointing to your new homepage (https://ndmitchell.com) over the nonexistent community.haskell.org one.
  • Using more modern doi.org links over portal.acm.org ones
  • etc.
• Using HTTPS over HTTP where possible
• Removing the Hoogle 4->5 section that's no longer relevant
• Correcting sections that are now incorrect
  • Updating instructions in Firefox section
  • Update "The Source Code" section to refer to GitHub and the GitHub issue tracker
  • etc.
• Redo "Folders" section and name it "Project Structure"

Plus just general cleanup and consistency (ex. being consistent with formatting of code blocks).

---

Of note are the dead links I removed in the Acknowledgements section.

I found the best fresh links I could for every dead link I removed, but I wasn't which links would be preferred when I found multiple, so just let me know which links would be preferred and I'll add them to the PR:

• Thomas "Bob" Davie
  • https://github.com/beelsebob
  • https://noordering.wordpress.com/
• Don Stewart
  • https://github.com/donsbot
  • https://donsbot.wordpress.com/
• Gaal Yahas
  • https://github.com/gaal
    • I left the existing link in as it's still functional, but while Gaal was last active on livejournal in April of 2011, they were active on GitHub in May of 2019 so it may be worth a switch
• Mike Dodds
  • https://github.com/septract
  • https://twitter.com/miike
• Niklas Broberg
  • https://github.com/niklasbroberg
  • https://research.chalmers.se/en/person/d00nibro

[lambdadog]

There's definitely more that can be done, especially going into the docs dir a little bit and doing some refactoring, but this is a happy starting point IMO

[ndmitchell]

Thanks, this is great work! I wouldn't worry too much about links for acknowledgements - most of the people there gave suggestions about Hoogle over a decade ago, so not sure it's even a relevant section to keep.