Help: Add release note for experimental ccmake support on Windows

Help/release/dev/ccmake-windows.rst

@@ -0,0 +1,6 @@
+ccmake-windows
+--------------
+
+* :manual:`ccmake(1)` may now be enabled on Windows when building
+  CMake from source.  This is experimental, and so is not included
+  in official distributions.