RELEASE_NOTES: fill in lib versions

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

RELEASE_NOTES

@@ -31,14 +31,14 @@
      diff n2.2 n2.3 doc/APIchanges` to show the list of added and deprecated
      APIs. FFmpeg 2.3 includes the following library versions:
 
-       • libavutil      xx.yy.1zz
-       • libavcodec     xx.yy.1zz
-       • libavformat    xx.yy.1zz
-       • libavdevice    xx.yy.1zz
-       • libavfilter    xx.yy.1zz
-       • libswscale     xx.yy.1zz
-       • libswresample  xx.yy.1zz
-       • libpostproc    xx.yy.1zz
+       • libavutil      52.92.100
+       • libavcodec     55.69.100
+       • libavformat    55.46.100
+       • libavdevice    55.13.102
+       • libavfilter     4.10.100
+       • libswscale      2. 6.100
+       • libswresample   0.19.100
+       • libpostproc    52. 3.100
 
      Please refer to the doc/APIChanges file for more information.