chore(github): PR template requiring to merge against dev

Author: hinell

.github/pull_request_template.md

@@ -1,8 +1,8 @@
-### LEGAL
+! MERGE AGAINST `DEV` BRANCH, NOT `MAIN`
+
+### LEGAL & CONTEXT
 - [ ] I've read the [CONTRIBUTING.md](../blob/main/CONTRIBUTING.md) and I'm fully aware of the terms
 - [ ] I've read the [LICENSE](../blob/main/LICENSE) and fully accept the terms and waive my rights over this contribution
+- [ ] I've [DISCUSSED](../discussions) this proposal or feature earlier (optional)
 
 ### SUMMARY
-
-### CONTEXT
-- [ ] I've [DISCUSSED](../discussions) this proposal or feature earlier