Create README.md in docs/devel

docs/devel/README.md

+# Developing Kubernetes
+
+Docs in this directory relate to developing Kubernetes.
+
+* **On Collaborative Development** ([collab.md](collab.md)): info on pull requests and code reviews.
+
+* **Development Guide** ([development.md](development.md)): Setting up your environment; tests.
+
+* **Hunting flaky tests** ([flaky-tests.md](flaky-tests.md)): We have a goal of 99.9% flake free tests.
+  Here's how to run your tests many times.
+
+* **GitHub Issues** ([issues.md](issues.md)): How incoming issues are reviewed and prioritized.
+
+* **Logging Conventions** ([logging.md](logging.md)]: Glog levels.
+
+* **Pull Request Process** ([pull-requests.md](pull-requests.md)): When and why pull requests are closed.
+
+* **Releasing Kubernetes** ([releasing.md](releasing.md)): How to create a Kubernetes release (as in version)
+  and how the version information gets embedded into the built binaries.