* Adding documentation for ``hint_enum`` uniform in shading_language.rst
Added explanation regarding ``hint_enum`` behaviour and usage in Uniforms section.
Also added a row in the Uniforms section table to reflect this new hint type
This PR is documentation regarding : godotengine/godot#94324
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Co-authored-by: A Thousand Ships <96648715+AThousandShips@users.noreply.github.com>