Added 0.3 release notes

RELEASE_NOTES.md

@@ -1,3 +1,12 @@
+# 0.3 (2016-04-21)
+
+* New process: "ror/rol" (for simple circular bit shift)
+* Ruby: runtime classes reside in a proper namespace: `Kaitai::Struct::Struct` and `Kaitai::Struct::Stream`, now just `KaitaiStruct` and `KaitaiStream`
+* Scala.js build: fully implemented, now compiler can be called on a web page as a JavaScript library
+* Implemented `process: ` for pre-processing input buffer of user types
+* Translator: allow coercing of different int types into each other
+* General code cleanup
+
 # 0.2 (2016-04-06)
 
 * Initial public release