update changelog

CHANGELOG.md

@@ -1,5 +1,14 @@
 ## Updates
 
+#### 23-Sep-2023
+
+- sokol_gfx.h gl: Allow to inject an external GL framebuffer id into the sokol-gfx default
+  pass. See PR https://github.com/floooh/sokol/pull/899 and issue https://github.com/floooh/sokol/issues/892
+  for details. Many thanks to @danielchasehooper for the discussion and PR!
+
+  Further down the road I want to make the whole topic more flexible while at the same time
+  simplifying the sokol-gfx API, see here: https://github.com/floooh/sokol/issues/904
+
 #### 22-Sep-2023
 
 - sokol_gfx.h: Fixed a Metal validation error on Intel Macs when creating textures (Intel Macs