[docs] Update AABB get_support description

[beyarkay]

This is a simple documentation edit. It updates the description of the get_support method in AABB to explain what a support point is.

[clayjohn]

Looks great! The final step before merging is to squash all the commits together so that the whole PR only contains 1 big commit with all your changes. We like to merge one commit at a time to keep the git history clean and navigable.

If you don't know how to do that, we have a helpful tutorial in the official documentation https://docs.godotengine.org/en/latest/community/contributing/pr_workflow.html#the-interactive-rebase

[beyarkay]

Apologies for the delay, I've squashed all commits

[beyarkay]

Just want to check about what the process is here, or what boxes need to be checked before this can be merged? Thanks! I'm sure you're all super busy with the Unity refugees so I really appreciate the time (:

[akien-mga]

You don't need to do anything further, once approved it's ready to merge by the production team, when we get to it.

[akien-mga]

Thanks! And congrats for your first merged Godot contribution 🎉