Would be nice to have a mention of the Spatial -> Node3D rename in the godot4 docs

[AndreLemay]

Just started playing around with Godot 4, having not touched or looked at Godot before.

Tutorial and docs are overall great, but as I started digging into stuff and googling various problems, I started finding all kinds of discussions and posts on the internet talking about doing stuff with "Spatials".

"What the heck is a spatial?" I ask myself - off to the docs. I see no class called Spatial, so I do a search, and all I find is stuff about Spatial shaders. Well that doesn't make much sense, shaders have nothing to do with what I'm looking up (usually basic "how to do weird rotations" kind of questions).

For a beginner, this is very confusing, because I keep finding people talking about how to do what I'm trying to do, but referring to things that just don't seem to exist. I was eventually able to figure it out by first just googling "godot spatial" and finding the godot 3 docs. From the description it seemed identical to Node3D, so I searched "godot spatial vs node3d" and finally came across the rename proposal, which made sense of everything.

Given how much time beginners are likely to spend googling relatively basic things, and how _un_likely the are to suspect that they might need to specify "godot 4" in their search (and you'd surely still get godot 3 answers as results), I think having some mention of this rename (especially in the tutorial) would be very helpful for other beginners like me.

At a glance, I think these might be useful pages to add a little disclaimer to:
https://docs.godotengine.org/en/stable/getting_started/introduction/key_concepts_overview.html#nodes
https://docs.godotengine.org/en/stable/getting_started/step_by_step/nodes_and_scenes.html#nodes
https://docs.godotengine.org/en/stable/tutorials/3d/introduction_to_3d.html#node3d-node
https://docs.godotengine.org/en/stable/classes/class_node3d.html

[clayjohn]

The rename is listed in the migrating to Godot 4 docs https://docs.godotengine.org/en/latest/tutorials/migrating/upgrading_to_godot_4.html

That being said, perhaps we need a specific callout in the introductory docs the first time that the Node3D is mentioned something like "by the way Node3D used to be called "Spatial" if you utilize any resources from Godot 3 you can treat references to "Spatial" nodes as "Node3D""

[AndreLemay]

Yup, I think that's all that's really needed.

As someone who never touched godot 3 and is just getting starting toying with the engine, I completely skipped over the migration docs because I didn't think it would be relevant in any way.