bpo-43325: Add FAQ entry for identity tests (GH-25168)

diff --git a/Doc/tutorial/datastructures.rst b/Doc/tutorial/datastructures.rst
index 5c6b65f..e42b380 100644
--- a/Doc/tutorial/datastructures.rst
+++ b/Doc/tutorial/datastructures.rst
@@ -661,9 +661,8 @@
 
 The comparison operators ``in`` and ``not in`` check whether a value occurs
 (does not occur) in a sequence.  The operators ``is`` and ``is not`` compare
-whether two objects are really the same object; this only matters for mutable
-objects like lists.  All comparison operators have the same priority, which is
-lower than that of all numerical operators.
+whether two objects are really the same object.  All comparison operators have
+the same priority, which is lower than that of all numerical operators.
 
 Comparisons can be chained.  For example, ``a < b == c`` tests whether ``a`` is
 less than ``b`` and moreover ``b`` equals ``c``.