Document steps for release candidate

Author: jack-berg

RELEASING.md

@@ -34,6 +34,37 @@ the `semantic-convention` release version, e.g. `v1.21.0.1`
   * This workflow will publish artifacts to maven central and will publish a GitHub release with
     release notes based on the change log.
 
+## Making release candidate locally
+
+* Follow steps to [prepare a new release](#preparing-a-new-release), but DO NOT [make the release](#making-the-release)
+* Check out release branch locally
+* Set required environment variables
+  * `export CI=true` - trick tooling to thinking this is the official release process, and sign artifacts
+  * `export GPG_PRIVATE_KEY=<private_key>`
+  * `export GPG_PASSWORD=<password>`
+  * `export SONATYPE_USER=<user>`
+  * `export SONATYPE_KEY=<key>`
+* Adjust version tag to include `-rc.<num>` suffix (i.e. `-rc.1` for the first release candidate) in [build.gradle.kts](./build.gradle.kts):
+
+  ```
+  var ver = semanticConventionsVersion
+  ver += "-rc.1" // <-- ADD THIS LINE
+  val release = findProperty("otel.release")
+  if (release != null) {
+    ver += "-" + release
+  }
+  if (snapshot) {
+    ver += "-SNAPSHOT"
+  }
+  version = ver
+  ```
+
+* Build and publish artifacts to staging repository
+  * Run `./gradlew assemble publishToSonatype closeSonatypeStagingRepository` 
+  * Notably, this stages the artifacts in sonatype and gives a chance for manual verification before publishing
+  * Publishing via the sonatype UI
+* After publishing, manually create Github release using the contents from the [CHANGELOG.md](./CHANGELOG.md)
+
 ## Credentials
 
 See [opentelemetry-java credentials](https://github.com/open-telemetry/opentelemetry-java/blob/main/RELEASING.md#credentials).