[DOC] Format specs

[BurdetteLamar]

This new document would eventually replace the format spec discussion at Kernel#sprintf, which would then link to the new doc.

One of the aims here is to make the discussion of a type specifier, say %b, sufficient in itself, without the reader having to carry a lot of info from other sections. In this beginning, only the one type specifier is detailed; others will follow in new PRs.

[jeremyevans]

See inline responses. Note that pushing additional commits after asking for a review can make review more difficult.

[BurdetteLamar]

Note that pushing additional commits after asking for a review can make review more difficult.

Sorry. I failed to resist the temptation to plug holes and correct errors. Will do better.

[BurdetteLamar]

I'm re-opening this because I really really want to see improvement to the doc for format specs.

I'll correct the errors cited by @jeremyevans, and seek common ground about the way the types should be documented.

[BurdetteLamar]

@jeremyevans, let's try for common ground on b and B.

[BurdetteLamar]

@jeremyevans, I'd originally thought to include this file in kernel.c, but later realized that it'll be better as a free-standing doc that all 4 *printf methods can link to. Therefore should be in doc/ not doc/kernel? If so, should the move be before this merge, or after?

[BurdetteLamar]

@jeremyevans Oh, and what about the many to-be-supplied sections? Keep adding to this PR, reviewing as we go? Or merge and add later?

[jeremyevans]

@jeremyevans, I'd originally thought to include this file in kernel.c, but later realized that it'll be better as a free-standing doc that all 4 *printf methods can link to. Therefore should be in doc/ not doc/kernel? If so, should the move be before this merge, or after?

Let's move to doc/ before the merge.

@jeremyevans Oh, and what about the many to-be-supplied sections? Keep adding to this PR, reviewing as we go? Or merge and add later?

Let's merge this after the move to doc/, then you can work on other specifiers.

[BurdetteLamar]

@jeremyevans, all set? I've removed the addition (kernel) to doc/.document.