request a use case for proposals

Signed-off-by: Krasi Georgiev <krasi-georgiev@users.noreply.github.com>

.github/ISSUE_TEMPLATE.md

@@ -10,7 +10,12 @@
     You can find more information at: https://prometheus.io/community/
 
 -->
+## Proposal
+**Use case. Why is this important?**
 
+*Nice to have' is not a good use case :)*
+
+## Bug Report
 **What did you do?**
 
 **What did you expect to see?**
@@ -41,6 +46,9 @@ insert configuration here
 insert configuration here (if relevant to the issue)
 ```
 
+
+
+
 * Logs:
 ```
 insert Prometheus and Alertmanager logs relevant to the issue here