Tweak the snapshot wording some more
Put the source commit in <meta name="revision">

For fun, to keep track of which commit snapshots are made from, and
potentially to generate a link showing changes since the snapshot.

The revision keyword is registered and accepted by validator.nu:
https://wiki.whatwg.org/wiki/MetaExtensions
Merge pull request #156 from foolip/meta-revision

Put the source commit in <meta name="revision">
Merge pull request #155 from foolip/tweak-snapshot-wording

Tweak the snapshot wording some more