We want to identify a document's creation date in the www.lsst.io documentation portal in order to provide context about new documents at are appearing.

We can start doing this by adapting Ook to look at the underlying Git repository and capturing the date of commits on the HEAD branch. In the general case, this is the date of the first commit. For technotes/documents, this should be the date of the second commit that modifies the source format (tex or rst) files to avoid capturing the date when the bot modified the content (an alternative might be too look at the commit author/committer info, and avoid commits by the bot, keeping in mind that sqrbot-jr/templatebot might impersonate the real user to some extent).