doc: Fix String.rsplit code example
doc: Fix String.rsplit code example

Fixes #36898.
Supersedes and closes #36951.

(cherry picked from commit e7fd0ec31f29b325edf0e17e8ba77a3ba0741d08)

ex/godot,ex/godot,ex/godot,ex/godot,ex/godot,ex/godot,ex/godot,ex/godot