Adding missing env variables for Spring SDK documentation (#4447)

* fix: adding missing env variables

- for REST configuration
- for gRPC configuration

* fix: adding correct REST port

versioned_docs/version-8.5/apis-tools/spring-zeebe-sdk/getting-started.md

@@ -124,6 +124,13 @@ ZEEBE_CLIENT_ID=xxx
 ZEEBE_CLIENT_SECRET=xxx
 ```
 
+Example environment variables to be set to configure gRPC and REST connection:
+
+```properties
+ZEEBE_GRPC_ADDRESS=http://127.0.0.1:26500/
+ZEEBE_REST_ADDRESS=http://127.0.0.1:8080/
+```
+
 Properties to be set using this approach:
 
 ```properties