chore(issue_templates): Add unused stacks to the list for release testing (#329)

Author: NickLarsenNZ

.github/ISSUE_TEMPLATE/release-from-scratch-testing.md

@@ -85,3 +85,32 @@ stackablectl demo install <DEMO_NAME>
 # --- IMPORTANT ---
 # Run through the nightly demo instructions (refer to the list above).
 ```
+
+## List of Stacks
+
+Some stacks are not used by demos, but still need testing in some way.
+
+> [!TIP]
+> Some of the stacks have a [tutorial](https://docs.stackable.tech/home/nightly/tutorials/) to follow.
+
+<!--
+    The following list was generated by:
+
+    # Using the real `yq` that follows the same interface as `jq`
+    yq -y --slurp '.[0] * .[1] | .allStacks - .usedStacks' \
+        <(cat demos/demos-v2.yaml| yq '{usedStacks: [.demos[] | .stackableStack]}') \
+        <(cat stacks/stacks-v2.yaml | yq '{allStacks: [.stacks | keys] | flatten}') \
+    | sed -e 's/^- /- [ ] /g' \
+    | sort
+-->
+
+- [ ] monitoring
+- [ ] observability
+- [ ] openldap
+- [ ] tutorial-openldap
+
+You can install the stack via:
+
+```shell
+stackablectl stack install <STACK_NAME>
+```