add sphinx theme to requirements

Author: Jamo197

docs/requirements.txt

@@ -6,3 +6,4 @@ oslash==0.6.3 ; python_version >= "3.10" and python_version < "4.0"
 referencing==0.35.1 ; python_version >= "3.10" and python_version < "4.0"
 rpds-py==0.22.3 ; python_version >= "3.10" and python_version < "4.0"
 typing-extensions==4.12.2 ; python_version >= "3.10" and python_version < "4.0"
+sphinx-rtd-theme==3.0.2 ; python_version >= "3.10" and python_version < "4.0"