WinRT: updated docs to include details of recently-expanded GLES2 support

docs/README-winrt.md

@@ -86,10 +86,11 @@ Here is a rough list of what works, and what doens't:
 * What partially works:
   * keyboard input.  Most of WinRT's documented virtual keys are supported, as
     well as many keys with documented hardware scancodes.
-  * OpenGL.  Experimental support for OpenGL ES 2 is available via a
-    Microsoft-modified version of the ANGLE project, as available at
-    https://github.com/msopentech/angle .  Support is currently limited to the
-    "winrt" branch, however support for the "future-dev" branch is planned.
+  * OpenGL.  Experimental support for OpenGL ES 2 is available via the ANGLE
+    project, using either MS Open Technologies' repository, at 
+    https://github.com/msopentech/angle (both the "winrt" and "future-dev"
+    branches are supported), or the official ANGLE repository, at
+    https://chromium.googlesource.com/angle/angle
   * SDLmain.  WinRT uses a different signature for each app's main() function.
     SDL-based apps that use this port must compile in SDL_winrt_main_NonXAML.cpp
     (in `SDL\src\main\winrt\`) directly in order for their C-style main()