[FABCJ-290] Add release guide

Signed-off-by: James Taylor <jamest@uk.ibm.com>

Author: jt-nti

RELEASING.md

@@ -0,0 +1,45 @@
+# Releasing
+
+The following artifacts are created as a result of releasing Fabric Chaincode Java:
+
+- docker images
+    - [fabric-javaenv](https://hub.docker.com/r/hyperledger/fabric-javaenv)
+- Java libraries
+    - [fabric-chaincode-shim](https://search.maven.org/search?q=a:fabric-chaincode-shim)
+    - [fabric-chaincode-protos](https://search.maven.org/search?q=a:fabric-chaincode-protos)
+
+**Note:** A docker image with a matching V.R version is required before releasing a new version of Fabric.
+
+## Before releasing
+
+It's useful to create an issue to keep track of each release, for example [Release v2.1.0](https://jira.hyperledger.org/browse/FABCJ-283).
+
+The following tasks are required before releasing:
+
+- Update version numbers in `build.gradle` files to the required version
+- Update test, sample, and docs files to match the new version
+- Create a new release notes file
+- Update the `CHANGELOG.md` file
+  
+  The `changelog.sh` script in `scripts` will prepopulate the changelog but you must check and edit the file manually afterwards as required
+
+See the [[FABCJ-289] release: 2.2.0 LTS](https://github.com/hyperledger/fabric-chaincode-java/pull/124) pull request for an example, although be careful to search for all versions in the codebase as they're easy to miss and things change!
+
+## Create release
+
+Creating a GitHub release on the [releases page](https://github.com/hyperledger/fabric-chaincode-java/releases) will trigger the build to publish the new release.
+
+When drafting the release, create a new tag for the new version (with a `v` prefix), e.g. `v2.1.4`
+
+See previous releases for examples of the title and description.
+
+## Publish Java libraries
+
+Log on to [https://oss.sonatype.org/#welcome] and _manually click two buttons_ to publish the JARs which were pushed by the release build.
+
+## After releasing
+
+- Update version numbers in `build.gradle` files to the next version
+- Update test, sample, and docs files to match the new version
+
+See the [Bump version to 2.2.1](https://github.com/hyperledger/fabric-chaincode-java/pull/127) pull request for an example. It should include almost all the files changed to prepare for the release, except for the release notes and changelog which do not need updating.