Please point to stable or versioned docs

[QuLogic]

Looking at matplotlib.org request logs, I see 2.5k req/day that 404 and come from matplotlib.org.cn. They all point to paths such as /images/... or /_static/.... Looking at some of the pages, I also see some links to top-level pages like /api/.... The top-level files were unwieldy, could disappear at any time as versions were release, and are no longer updated. At some point in the future, we plan to remove them entirely.

Please point image or page links to /stable/..., or, if you aren't certain you will always be up-to-date, a specific version such as /3.8.0/...