doc: Clarify capturing .readouterr() return value (#13222)

This got added in 38fb6aa, where the "The
return value ... changed" made a lot of sense. However,
9c5da9c removed the "versionadded" without
adjusting the wording.

Also see 3a4435f.

Author: The-Compiler

Diff for: doc/en/how-to/capture-stdout-stderr.rst

@@ -131,7 +131,7 @@ test from having to care about setting/resetting
 output streams and also interacts well with pytest's
 own per-test capturing.
 
-The return value from ``readouterr`` changed to a ``namedtuple`` with two attributes, ``out`` and ``err``.
+The return value of ``readouterr()`` is a ``namedtuple`` with two attributes, ``out`` and ``err``.
 
 If the code under test writes non-textual data (``bytes``), you can capture this using
 the :fixture:`capsysbinary` fixture which instead returns ``bytes`` from

Diff for: doc/en/how-to/parametrize.rst

@@ -29,10 +29,6 @@ pytest enables test parametrization at several levels:
 
 .. regendoc: wipe
 
-
-
-    Several improvements.
-
 The builtin :ref:`pytest.mark.parametrize ref` decorator enables
 parametrization of arguments for a test function.  Here is a typical example
 of a test function that implements checking that a certain input leads