Help: Add release notes for test-output-truncation

Add missing release notes for test-output-truncation.

Issue: #23206

Help/release/dev/ctest-output-truncation.rst

@@ -0,0 +1,11 @@
+ctest-output-truncation
+-----------------------
+
+* :manual:`ctest(1)` gained a ``--test-output-truncation`` option (and
+  corresponding :variable:`CTEST_CUSTOM_TEST_OUTPUT_TRUNCATION` variable) to
+  specify the truncation mode once the maximum test output size has been
+  reached. Possible values are ``tail`` (default), ``middle`` or ``head``.
+* :manual:`cmake-presets(7)` files now support schema version ``5``.
+* :manual:`cmake-presets(7)` files gained support for specifying a
+  ``testOutputTruncation`` field in test presets, which specifies the truncation
+  mode once the maximum test output size has been reached.