Add epic template

.github/ISSUE_TEMPLATE/epic.md

@@ -0,0 +1,40 @@
+---
+name: Epic Issue Template
+about: Track Epics
+title: "[Epic] "
+labels: epic
+assignees: ''
+
+---
+
+2023 Milestones: https://notes.status.im/s/iylE6wdli#
+
+**Epic label**: `label`
+<!-- Remove tracks as needed -->
+**Priority Tracks**: Secure Scalability, Production Readiness, Growth, Generating Revenue (Sustainability & Longevity).
+**Due date**:
+
+# Summary
+
+<!-- Provide a high level summary of the Epic --> 
+
+# Justification
+
+<!-- Justify the Epic in the context of the priority tracks and project/collective strategies -->
+
+# Milestones
+
+## Eco Dev
+
+- [ ] Milestone title or link
+...
+
+## Research
+
+- [ ] Milestone title or link
+
+## nwaku
+
+## js-waku
+
+## go-waku