OpenXR passthrough documentation refers to OVRMobile plugin

[dsnopek]

Your Godot version:

3.x

Issue description:

I don't know the correct code, because I've never done passthrough in Godot 3 with the OpenXR plugin, so I can't fix it (at least without some more research) but I noticed when looking at the docs (because someone linked them on Discord) that the code is loading part of the OVRMobile plugin which can't be right. :-)

This should be loading something from the OpenXR plugin instead.

URL to the documentation page:

https://docs.godotengine.org/en/stable/tutorials/vr/openxr/passthrough.html

[tetrapod00]

It's not there in the 4.x docs.

[dsnopek]

Yes, this is an issue in the 3.x docs, and is still there:

https://docs.godotengine.org/en/3.6/tutorials/vr/openxr/passthrough.html

However, I don't know if we care to fix it at this point?

[tetrapod00]

Fixing the 3.x docs is mostly not a priority at this point. But if anyone makes a PR for it we'll take it (assuming there are reviewers available).

I've been going through all the old issues and tagging the 3.x specific issues with the 3.x milestone. If and when the 3.x docs are officially no longer maintained here, we can look at these old issues one more time, confirm they are no longer relevant, and close them as a batch.