Update release_steps.md (#10568)

.github/ISSUE_TEMPLATE/release_steps.md

@@ -42,7 +42,11 @@ This steps have to be followed always when preparing a new release.
 - [ ] Check `pom.xml` dependencies are all in fixed stable versions ( no `-SNAPSHOT` usage release). If not, You use the action  [`Update dependencies versions`](https://github.com/geosolutions-it/MapStore2/actions/workflows/update_dependencies_versions.yml) to fix them, setting:
     - [ ] the branch to `YYYY.XX.xx`
     - [ ] the of geostore, http_proxy and mapfish-print versions accordingly with the [MapStore release calendar](https://github.com/geosolutions-it/MapStore2/wiki/MapStore-Release-Calendars)
-- [ ] Check that [MapStoreExtension](https://github.com/geosolutions-it/MapStoreExtension) repository is aligned and working
+- [ ] Check that [MapStoreExtension](https://github.com/geosolutions-it/MapStoreExtension) repository is aligned and working. 
+- [ ] Run the [Submodule Update](https://github.com/geosolutions-it/MapStoreExtension/actions/workflows/submodules_update.yml) of [MapStoreExtension](https://github.com/geosolutions-it/MapStoreExtension) to generate the `SampleExtension.zip` to use for testing.
+    - [ ] Use workflow from `YYYY.XX.xx` branch
+    - [ ] Wait for completition
+    - [ ] Download the `Artifacts.zip` that contains `SampleExtension.zip` from the execution of the `checks` action on the branch `YYYY.XX.xx`. This can be used for tests.
 - [ ] Test on QA [https://qa-mapstore.geosolutionsgroup.com/mapstore/](https://qa-mapstore.geosolutionsgroup.com/mapstore/)
   - [ ] Test **everything**, not only the new features
   - [ ] Test the creation of a standard project starting in from the stable branch and with the internal backend, so: