Add release notes for 0.9.0 (#581)

Author: xerial

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 +1,33 @@
 # 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 extension 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 methods (e.g., unpackInt, unpackExtension, etc.),
+you need to read unpackExtensionHeader first, and if extHeader.isTimestampType is true, call unpackTimestamp(ext).
+
+When reading Timestamp values, [java.time.Instant](https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/time/Instant.html) will be returned.
+You can extract the unixtime with Instant.getEpochSecond(), unixtime with milliseconds resolution with Instant.toEpochMilli(), and nano-resolution time with Instant.getNano().
+
+As TimestampValue is a sub class of ExtensionValue, your code traversing MessagePack data with MessageUnpacker.unpackValue should require no change.
+
+
+* Added Timestamp support [#565](http://github.com/msgpack/msgpack-java/pull/565) and low-level APIs [#580](https://github.com/msgpack/msgpack-java/pull/580) for
+reading timestamp values.
+
+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)