docs: Enhance the usage of rtol and atol arguments in pd.testing.assert_frame_equal

Author: tan-i-ham

pandas/_testing/asserters.py

@@ -1158,7 +1158,10 @@ def assert_frame_equal(
         Specify how to compare internal data. If False, compare by columns.
         If True, compare by blocks.
     check_exact : bool, default False
-        Whether to compare number exactly.
+        Whether to compare number exactly. If False, the comparison uses the
+        relative tolerance (`rtol`) and absolute tolerance (`atol`)
+        parameters to determine if two values are considered close,
+        according to the formula: `|a - b| <= (atol + rtol * |b|)`.
 
         .. versionchanged:: 2.2.0