doc: update release_notes by taking the ones from release/1.2

doc/RELEASE_NOTES

 Release Notes
 =============
 
-* 0.10 "Freedom"  January, 2012
+* 1.2 "Magic"  March, 2013
 
 
 General notes
@@ -14,9 +14,3 @@ accepted. If you are experiencing issues with any formally released version of
 FFmpeg, please try git master to check if the issue still exists. If it does,
 make your report against the development code following the usual bug reporting
 guidelines.
-
-Of big interest to our Windows users, FFmpeg now supports building with the MSVC
-compiler. Since MSVC does not support C99 features used extensively by FFmpeg,
-this has been accomplished using a converter that turns C99 code to C89. See the
-platform-specific documentation for more detailed documentation on building
-FFmpeg with MSVC.