DOC: Enforce Numpy Docstring Validation for pandas.Index.unique (#58399)

* DOC: add RT03 to pandas.Index.unique

* DOC: remove pandas.Index.unique

Author: tuhinsharma121

ci/code_checks.sh

@@ -153,7 +153,6 @@ if [[ -z "$CHECK" || "$CHECK" == "docstrings" ]]; then
         -i "pandas.Index.take PR01,PR07" \
         -i "pandas.Index.to_list RT03" \
         -i "pandas.Index.union PR07,RT03,SA01" \
-        -i "pandas.Index.unique RT03" \
         -i "pandas.Index.view GL08" \
         -i "pandas.Int16Dtype SA01" \
         -i "pandas.Int32Dtype SA01" \

pandas/core/indexes/base.py

@@ -2647,6 +2647,7 @@ def unique(self, level: Hashable | None = None) -> Self:
         Returns
         -------
         Index
+            Unique values in the index.
 
         See Also
         --------