Merge pull request #74 from ilius/master

Fix typo in README.md: GLFW3 -> pygame

README.md

@@ -26,7 +26,7 @@ built-in rendering backend integrations (pygame, cocos2d, etc.). If you don't
 want to install all additional dependencies you can always use bare
 `pip instal imgui` command or select a specific set of extra requirements:
 
-* for GLFW3 backend use `pip install imgui[pygame]`
+* for pygame backend use `pip install imgui[pygame]`
 * for GLFW3 backend use `pip install imgui[glfw]`
 * for SDL2 backend use `pip install imgui[sdl2]`
 * for Cocos2d backend use `pip install imgui[cocos2d]`