Adds link of the Metal port.

I just implmeneted the native Metal port of NanoVG. ;)

README.md

@@ -101,7 +101,8 @@ See the header file [nanovg.h](/src/nanovg.h) for API reference.
 ## Ports
 
 - [DX11 port](https://github.com/cmaughan/nanovg) by [Chris Maughan](https://github.com/cmaughan)
-- [bgfx port](https://github.com/bkaradzic/bgfx/tree/master/examples/20-nanovg) by [Branimir Karadžić](https://github.com/bkaradzic) 
+- [Metal port](https://github.com/ollix/MetalNanoVG) by [Olli Wang](https://github.com/olliwang)
+- [bgfx port](https://github.com/bkaradzic/bgfx/tree/master/examples/20-nanovg) by [Branimir Karadžić](https://github.com/bkaradzic)
 
 ## Projects using NanoVG