Autogen: Add AUTOUIC_SEARCH_PATHS release notes

Help/release/dev/Autogen_uic_paths.rst

+AutoGen uic paths
+-----------------
+
+* Variable :variable:`CMAKE_AUTOUIC_SEARCH_PATHS` was introduced to
+  allow :variable:`CMAKE_AUTOUIC` to search for ``foo.ui`` in more
+  places than the vicinity of the ``ui_foo.h`` including file.
+
+* The new target property :prop_tgt:`AUTOUIC_SEARCH_PATHS` was introduced to
+  allow :prop_tgt:`AUTOUIC` to search for ``foo.ui`` in more
+  places than the vicinity of the ``ui_foo.h`` including file.