Describe the git subtree process

Author: slinkydeveloper

README.md

@@ -416,3 +416,15 @@ To publish local snapshots of the project:
 ```shell
 ./gradlew -DskipSigning publishToMavenLocal
 ```
+
+To update the [`proto`](https://github.com/restatedev/proto/) git subtree:
+
+```shell
+git subtree pull --prefix sdk-common/src/main/proto/ git@github.com:restatedev/proto.git main --squash
+```
+
+To update the [`service-protocol`] git subtree:
+
+```shell
+git subtree pull --prefix sdk-core/src/main/service-protocol/ git@github.com:restatedev/service-protocol.git main --squash
+```

development/release.md

@@ -2,6 +2,7 @@
 
 To release sdk-java:
 
+* First make sure `service-protocol` and `proto` subtrees are updated to the latest version. See the main [README.md](../README.md#contributing-to-the-sdk)
 * Change the version to the desired version using the [Bump version workflow](https://github.com/restatedev/sdk-java/actions/workflows/bump.yaml).
 * Merge the auto generated PR
 * Wait for CI on main to execute the release