Add changeset for spec naming clarification (#596)

Author: TabishB

.changeset/spec-naming-clarification.md

@@ -0,0 +1,8 @@
+---
+"@fission-ai/openspec": patch
+---
+
+### Bug Fixes
+
+- Clarified spec naming convention — Specs should be named after capabilities (`specs/<capability>/spec.md`), not changes
+- Fixed task checkbox format guidance — Tasks now clearly require `- [ ]` checkbox format for apply phase tracking