Update doc

[xoac]

apply rustfmt on this lib
sync doc in src/lib.rs with information in README.md

[tailhook]

I'm okay with doc update. But any specific reason why you have applied rustfmt? Most (if not all) things aren't improvements here, some are harmful. To name a few:

1. Bytes in declaration of buf (date.rs:32) are aligned to have newlines at separators T and .
2. Loop comment in date.rs:278 became in the wrong place
3. I like the contrast between an = assignment and configuration="parameters" (spaces around equals sign).

I understand rustfmt is a useful tradeoff for projects with high contribution traffic where it's easier to settle on rustfmt than to teach everyone good style. But this crate is prettly low-maintenance. And there is no need for such extra changes.

[xoac]

I used rustfmt because it's done im my IDE on save. So no general purpose.

I think I can come back to master, Add skip attributes and then do rustfmt and update doc.

or just update doc. whatever you prefer

[tailhook]

Thanks, I prefer just updating docs.

[xoac]

Done

[tailhook]

Merged. Thanks!