Have the docs website tell you the latest version of a page that existed

**Your Godot version:**

N/A

**Issue description:**

When reading [this thread](https://www.reddit.com/r/godot/comments/x6dtfs/how_to_get_the_contact_position_of_a_rigidbody2d/), you can notice that Nkzar's link is dead, leading to a "page not found" in the docs.

This is because Nkzar pasted a url with "stable" within rather than the engine version which was stable at the time, and since this was posted 4years ago, the Physics2DDirectBodyState doesn't exist anymore (it was renamed with "2D" at the end of the name).

Through trial and error by changing the version in the url, you can notice that the page existed back in godot 3. But I think it would be better if the website directly told you if the page you are looking for existed in an earlier version or will exist in a future version.

That would especially be useful for user that don't know about the "version system" hidden in the url.

I am unsure wether this is an issue for godot-docs, sphinx, or read the docs.

**URL to the documentation page (if already existing):**

The "Page not found" page