Latest version placeholder

I originally asked about this here https://github.com/docker-library/docs/pull/1802#discussion_r497240482 but I didn't get an answer, so I figured I'd open an issue instead to discuss it.

Is there any way to dynamically replace this <version> with a placeholder? I dug through the scripts in this repo and I didn't find any relevant placeholders.

Ideally, I'd like a %%LATEST_VERSION%% placeholder that would basically be the version number that the latest tag shares.

I've already gotten a question from a user recently who is new to Docker asking "do I need to replace <version>?" so I think this should be improved.

I realize that this is probably non-trivial because the latest tag doesn't directly map to a specific version because of how tagging works. Maybe there's a way to hook into the docs generator to provide additional placeholders? We could write a simple script that extracts the relevant info based on some heuristic.

Start by reviewing the discussion in docker-library/docs#1802 and the repository scripts referenced in the issue. Trace how the docs generator handles placeholders and how the latest tag is represented. Done means the project has a decided, documented approach for exposing the latest version, with the behavior verified in the generator workflow.