Animation Tree documentation contains small typo

[SimoneRizzuto]

Your Godot version:

Issue description:
There is a small typo in the documentation:
"...a node has to be connected to to the output..."

Obviously should be "connected to the output", no duplicate "to".

FULL SENTENCE:
"In order for animations to play, a node has to be connected to to the output. You can add nodes from the Add Node.. menu or by right clicking an empty space:"

URL to the documentation page:
https://docs.godotengine.org/en/latest/tutorials/animation/animation_tree.html#blend-tree