added missing bug fix note

docs/docs/release_notes.xml

@@ -59,6 +59,9 @@ Bug fixes:
      murmur_hash3() to avoid violation of the strict aliasing rule. In
      particular, the previous version didn't work correctly in gcc 4.7.2 when
      optimizations were enabled.
+   - Visual Studio 2012's iostreams library has a bug which caused the
+     iosockstream to crash on use.  This version of dlib has been changed to
+     avoid triggering this bug.
 
 Other:
    - Refactored the Platt scaling code a little. Now there is a function,