Add intersection into _index_shared_docs

pandas/core/indexes/base.py

@@ -2370,8 +2370,7 @@ def union(self, other, sort=None):
     def _wrap_setop_result(self, other, result):
         return self._constructor(result, name=get_op_result_name(self, other))
 
-    def intersection(self, other, sort=False):
-        """
+    _index_shared_docs['intersection'] = """
         Form the intersection of two Index objects.
 
         This returns a new Index with elements common to the index and `other`.
@@ -2405,6 +2404,9 @@ def intersection(self, other, sort=False):
         >>> idx1.intersection(idx2)
         Int64Index([3, 4], dtype='int64')
         """
+
+    @Appender(_index_shared_docs['intersection'])
+    def intersection(self, other, sort=False):
         self._validate_sort_keyword(sort)
         self._assert_can_do_setop(other)
         other = ensure_index(other)

pandas/core/indexes/interval.py

@@ -1112,6 +1112,7 @@ def equals(self, other):
     def overlaps(self, other):
         return self._data.overlaps(other)
 
+    @Appender(_index_shared_docs['intersection'])
     @_setop_check(op_name='intersection')
     def intersection(self, other, sort=False):