docs: Documentation fixes for CoglBitmap
docs: Documentation fixes for CoglBitmap

• Use the same style for the Cogl API reference as the one used for
  the Clutter API reference.

• Fix the introspection annotations for cogl_bitmap_get_size_from_file()

djdeath/cogl,Distrotech/cogl,gcampax/cogl,spatulasnout/cogl,djdeath/cogl-android,spatulasnout/cogl,gcampax/cogl,Distrotech/cogl,gcampax/cogl,collects/cogl,collects/cogl,Distrotech/cogl,djdeath/cogl-android,Distrotech/cogl,djdeath/cogl,djdeath/cogl,djdeath/cogl-android,gcampax/cogl