update asserters doc string

Author: topper-123

pandas/_testing/asserters.py

@@ -266,10 +266,9 @@ def assert_index_equal(
     left : Index
     right : Index
     exact : bool or {'equiv'}, default 'equiv'
-        Whether to check the Index class, dtype and inferred_type
-        are identical. If 'equiv', RangeIndex can be substituted for
-        Int64Index and integer dtypes will be equivalent to each other and
-        float dtypes equivalent to each other.
+        It True, check that the Index class, dtype and inferred_type are identical.
+        If 'equiv', numeric indexes will only be compared by dtype and inferred_type.
+        It False, do not check that Index class, dtype and inferred_type are identical.
     check_names : bool, default True
         Whether to check the names attribute.
     check_less_precise : bool or int, default False