documentation - brief descriptions for bpy api files.

source/blender/python/intern/bpy_library.c

@@ -22,6 +22,12 @@
 
 /** \file blender/python/intern/bpy_library.c
  *  \ingroup pythonintern
+ *
+ * This file exposed blend file library appending/linking to python, typically
+ * this would be done via RNA api but in this case a hand written python api
+ * allows us to use pythons context manager (__enter__ and __exit__).
+ *
+ * Everything here is exposed via bpy.data.libraries.load(...) context manager.
  */
 
 /* nifty feature. swap out strings for RNA data */