Add note

README.md

@@ -96,6 +96,13 @@ $ git tag v0.x.y
 $ git push origin v0.x.y
 ```
 
+To generate a release notes, you can use this command line:
+```
+$ git log v(last version).. --oneline | cut -f 2- -d ' ' | perl -npe 's/(.*)\(\#([0-9]+)\)/* \1\(\#\2\)\[http:\/\/github.com\/msgpack\/msgpack-java\/pull\/\2\]/g'
+```
+
+#### Publishing to Sonatype from Local Machine
+
 If you need to publish to Maven central using a local machine, you need to configure [sbt-sonatype](https://github.com/xerial/sbt-sonatype) plugin. First set Sonatype account information (user name and password) in the global sbt settings. To protect your password, never include this file in your project.
 
 ___$HOME/.sbt/(sbt-version)/sonatype.sbt___

RELEASE_NOTES.md

@@ -1,5 +1,26 @@
 # Release Notes
 
+## 0.9.0
+
+This version support reading and writing [Timestamp values](https://github.com/msgpack/msgpack/blob/master/spec.md#timestamp-extension-type).
+Packer and unpacker interfaces added pack/unpackTimestamp methods.
+
+Timestamp value in MessagePack is an extention type value whose code is -1. If MessgageUnapcker.unpackValue method is used,
+TimestampValue object can be retrieved automatically. If you are using low-level unpack method (e.g., unpackInt, unpackExtension, etc.),
+you need to read unpackExtHeader first, and if extHeader.isTimestamp is true, call unpackTimestamp(ext).
+
+* Timestamp support (#565)[http://github.com/msgpack/msgpack-java/pull/565]
+
+Dependency updates:
+* Update jackson-databind to 2.10.5.1 (#559)[http://github.com/msgpack/msgpack-java/pull/559]
+
+Internal updates:
+* Update akka-actor to 2.6.14 (#579)[http://github.com/msgpack/msgpack-java/pull/579]
+* Fix for Scala 2.13 syntax (#577)[http://github.com/msgpack/msgpack-java/pull/577]
+* Update airframe-json, airspec to 21.6.0 (#576)[http://github.com/msgpack/msgpack-java/pull/576]
+* Update scala-library to 2.13.6 (#568)[http://github.com/msgpack/msgpack-java/pull/568]
+* Update sbt to 1.5.3 (#575)[http://github.com/msgpack/msgpack-java/pull/575]
+
 ## 0.8.24
 
 * Rebuild with JDK8 for Android compatibility [#567](https://github.com/msgpack/msgpack-java/pull/567)