Add ProtableGL integration link

README.md

@@ -195,6 +195,7 @@ pntr_image_type pntr_get_file_image_type(const char* filePath);
 | [pntr_nuklear](https://github.com/RobLoach/pntr_nuklear) | [Nuklear](https://github.com/Immediate-Mode-UI/Nuklear) immediate-mode graphical user interface for pntr |
 | [pntr_aseprite](https://github.com/RobLoach/pntr_aseprite) | Use [Aseprite](https://github.com/RobLoach/pntr_aseprite) animated sprites in pntr |
 | [pntr_tiled](https://github.com/RobLoach/pntr_tiled) | Display [Tiled](https://www.mapeditor.org/) 2D level editor maps in pntr |
+| [pntr_portablegl](https://github.com/RobLoach/pntr_portablegl) | Use the OpenGL-esque software rendering library, [PortableGL](https://github.com/rswinkle/PortableGL), in pntr |
 
 ## Development