Help: add release notes for ctest_start() changes

Help/release/dev/ctest-start-args-rework.rst

@@ -0,0 +1,7 @@
+ctest-start-args-rework
+-----------------------
+
+* The :command:`ctest_start` command has been reworked so that you can simply
+  call ``ctest_start(APPEND)`` and it will read all the needed information from
+  the TAG file. The argument parsing has also been relaxed so that the order of
+  the arguments is less significant.