Update wording, links in key projects page

[brainwane]

A few link fixes, clearer explanations regarding wheel, packaging, pip, and distlib, and a few wording/capitalization fixes.

[ncoghlan]

Several suggestions inline. Perhaps it would make sense to split the purely mechanical GitHub word mark fix out from the more subjective updates to the project descriptions?

[brainwane]

Several suggestions inline. Perhaps it would make sense to split the purely mechanical GitHub word mark fix out from the more subjective updates to the project descriptions?

I appreciate the note; if I'd been more disciplined I would have done that! If this PR drags on for several days then I'll probably do that. :-)

[bhrutledge]

Thanks for asking for my review! Just some minor suggestions/questions, which I don't feel should block merging this.

Also, I couldn't make the sugestion, but http://docs.pipenv.org/ is an expired domain name. This works: https://pipenv.kennethreitz.org/en/latest/.

[bhrutledge]

Also, thanks for putting the time into this, and the attention to detail. I think it’s a nice improvement.

[brainwane]

Added several projects and improved wording and detail for several existing projects.

[uranusjr]

I’m on my phone right now; there are several casing and format inconsistencies that could use some fixing. I see at least three different renderings for distlib alone: Distlib, distlib, and distlib.

[brainwane]

I've fixed up a few formatting inconsistencies (addressing @uranusjr's comments) as best I could given the inconsistency of the formatting beforehand. Also I've now added web links to the IRC channels.

I believe this is ready to merge and would substantially improve the Key Projects page when merged, with better basic overviews of many important packaging projects. I respect that this PR is a chance to fix a bunch of formatting and wording stuff in a piece of documentation that hasn't gotten a ton of love lately. May I ask that we try to merge this is, and make follow-up PRs or issues about further improving casing/formatting consistency, advising users in more detail about gotchas, and so on?