DOC: fix ES01,RT03,SA01 for pandas.MultiIndex.remove_unused_levels (#59366)

Author: tuhinsharma121

ci/code_checks.sh

@@ -73,7 +73,6 @@ if [[ -z "$CHECK" || "$CHECK" == "docstrings" ]]; then
  -i "pandas.MultiIndex.get_level_values SA01" \
  -i "pandas.MultiIndex.get_loc_level PR07" \
  -i "pandas.MultiIndex.names SA01" \
- -i "pandas.MultiIndex.remove_unused_levels RT03,SA01" \
  -i "pandas.MultiIndex.reorder_levels RT03,SA01" \
  -i "pandas.MultiIndex.sortlevel PR07,SA01" \
  -i "pandas.MultiIndex.to_frame RT03" \

pandas/core/indexes/multi.py

@@ -2091,9 +2091,22 @@ def remove_unused_levels(self) -> MultiIndex:
  appearance, meaning the same .values and ordering. It will
  also be .equals() to the original.
 
+ The `remove_unused_levels` method is useful in cases where you have a
+ MultiIndex with hierarchical levels, but some of these levels are no
+ longer needed due to filtering or subsetting operations. By removing
+ the unused levels, the resulting MultiIndex becomes more compact and
+ efficient, which can improve performance in subsequent operations.
+
  Returns
  -------
  MultiIndex
+ A new MultiIndex with unused levels removed.
+
+ See Also
+ --------
+ MultiIndex.droplevel : Remove specified levels from a MultiIndex.
+ MultiIndex.reorder_levels : Rearrange levels of a MultiIndex.
+ MultiIndex.set_levels : Set new levels on a MultiIndex.
 
  Examples
  --------