List of pages from versions 9, 10, and 11 that don't exist in "current"

Hi there,

Does anyone have an easy way of seeing which pages from the 9.x, 10,
or 11 docs don't have a "current" version?

For example: https://www.postgresql.org/docs/11/recovery-config.html

Apologies in advance if there is a better list to email about this, let me know.

More context below, in case helpful.

Cheers,
Michael

For context, I've built a Firefox extension that redirects old
versions of the docs to their "current" version, except when either:
* you're already on the docs, or
* when a "current" version of the page doesn't exist.

Pages from older versions like 7.x and 8.x seem to be less of an issue
on search engines, so I'm thinking of supporting 9.0+ to reduce the
number of deprecated pages (wishful thinking perhaps?). Any advice
would be very welcome.

A response along the lines of "There are a LOT of these, please find
another way." would also be incredibly welcome.

I'm aware of some discussions in the past on ways to get search
engines to rank the "current" version of a page higher. It sounded
like a tough problem, so while people work out how to solve the root
issue(s), I thought a browser extension might help a little.

Code so far (MIT):
https://github.com/mchristofides/pg_docs_bot/

Extension link (v0.7, would like v1 to have this feature):
https://addons.mozilla.org/en-US/firefox/addon/pg_docs_bot/