I haven't put [code] bbcode around the amount of the AnimationNodeAdd* classes
because it's not exposed to GDScript.
Same for the +add, -add, etc. labels: they're just labels you can find in the
AnimationTree bottom panel.
(cherry picked from commit d0eb99f970)
In many of the XML files it had been noted that when the documentation
refers to a return value, both "Return" and "Returns" are used. This
has now been fixed to only say "Returns".
Fixes#28867
(cherry picked from commit 426bcc9941)
