Create a way to display and manage content freshness

Broken out of https://github.com/nodejs/nodejs.org/issues/7197

Add metadata on pages to display last update (git has this info of course)

• we noted a distinction between last reviewed (by a human) and last updated
• eventually, create a means to flag when content gets stale, perhaps via an action that opens issues, if one exists

@AugustinMauroy had these thoughts

I'm more in favour of the version used in the example. Because a date has no value in relation to the runtime. In addition, having the version allows the contributor/collaborator to know if a document needs to be revised.
And from a functional point of view, I think we should add a bit to the MetaBar that allows you to install (redirect to the installation of the correct version).

This is interesting, but would create LTS rollover moments where we have all to review all content. I think that would quickly become the norm, twice a year.
I suppose that's better than arbitrary dates, TBH.

Given that thought experiment, maybe we build on nodejs/nodejs.org#7294 and build something that asks the owners to review the content twice a year?

No files, tests, or entry points are named. Start by reviewing the linked issues nodejs/nodejs.org#7197 and #7294, then clarify whether the scope is update metadata, human review dates, version indicators, or automated stale-content issues. Done should include an agreed design and an explicit review or freshness workflow.