Apple: Fixed example_osx_opengl2, renamed to example_apple_opengl2 + misc comments

examples/imgui_impl_osx.h

@@ -1,5 +1,10 @@
 // ImGui Platform Binding for: OSX / Cocoa
 // This needs to be used along with a Renderer (e.g. OpenGL2, OpenGL3, Vulkan, Metal..)
+// [BETA] Beta bindings, not well tested. If you want a portable application, prefer using the Glfw or SDL platform bindings on Mac.
+
+// Issues:
+// [ ] Platform: Keys are all generally very broken. Best using [event keycode] and not [event characters]..
+// [ ] Platform: Mouse cursor shapes and visibility are not supported (see end of https://github.com/glfw/glfw/issues/427)
 
 @class NSEvent;
 @class NSView;