templates: add new-feature template

Propose a process checklist for implementing a new feature.

This may not be universally accepted or widely used.  But, I had some
process notes sitting around, and maybe they'll be useful as a starting
point.

.github/ISSUE_TEMPLATE/new-feature.md

@@ -0,0 +1,31 @@
+---
+name: Implement a feature
+about: Propose a design for a new feature
+---
+
+# Feature proposal
+
+## Description
+
+<!-- describe the concept and proposed implementation, in specific detail -->
+
+## Implementation PRs
+
+<!-- after PRs are posted, link them here, in a bulleted list so GitHub will show their status -->
+
+## Implementation steps
+
+- [ ] Create tracker ticket with initial design (above)
+- [ ] Initial discussion and refinement in the ticket
+- [ ] Add `meeting` label
+- [ ] Discuss at community meeting
+- [ ] Further refinement
+  - [ ] Post draft [fedora-coreos-docs](https://github.com/coreos/fedora-coreos-docs/) PR, ideally before doing any implementation, to help identify design problems.
+- [ ] Update issue description with final proposal and post a comment saying that you did
+- [ ] Verify that rough consensus exists
+- [ ] Implement.  Post PR links in the section above.  In the description of each PR, link to this issue and specify the prerequisites for merging.
+  - [ ] Add kola test(s) for new feature
+- [ ] Land implementation PRs, in order
+- [ ] Wait for the functionality to reach FCOS stable
+- [ ] Land docs PR
+- [ ] Remove any ratcheting glue (e.g. workarounds in coreos-assembler)