Add remaining Use Case Issues.

[gkellogg]

This is a pretty straight forward copy/paste from the issue into the document, which is probably good enough for now.

Addresses #7, #8, #11, #12, #13, #17, #19, #31, and #35.

cc/ @nichtich, @anatoly-scherbakov.

[gkellogg]

Note, sadly no PR-preview on the UCR document.

[VladimirAlexiev]

@gkellogg thanks for this! However I'm wondering whether it's a bit early.

• there's still a lot of discussion on many of the UCRs, basically to understand what we want
• UCRs in the UCR spec should include only agreed ("crystallized") items, not all discussion items
• I just added #42 and #43

@ioggstream @pchampin what do you think?

• I don't know much about how the editorial process happens
• Maybe Gregg did the right thing to start the UCR spec, and now we should appoint owners per section/topic, and they take the responsibility of maintaining the section as discussions unfold on github, and as consensus is reached?

[gkellogg]

This PR was discussed in the 2022-07-06 meeting, and it was decided to not merge now, and wait until more use cases have been identified and reconciled.