RefCounted.free() can't be called.

**Your Godot version:**
v4.0.stable.official

**Issue description:**
In the documentation page,
`RefCounteds therefore do not need to be freed manually with Object.free.`
It doesn't mean "You can't call Object.free()", right?
`Autocomplete` autocompleted `free` but it makes an error.
I should use Tween.kill() instead of Tween.free().
However, nobody say "don't use `free`".

**URL to the documentation page:**
https://docs.godotengine.org/en/stable/classes/class_refcounted.html#description