Edits on dev guide and rename it to CONTRIBUTING.md

CONTRIBUTING.md

@@ -0,0 +1,63 @@
+# Contributing Guide
+
+This doc is the contributing guideline for Kubeflow/common developers.
+
+## Git development workflow
+
+We use the [GitHub flow](https://guides.github.com/introduction/flow/) for development. Please check it out to get familiar with the process.
+
+## Before PR submission
+
+Before submitting a pull request, please make sure the code passes all the tests and is free of lint errors. The following sections outlines the instructions.
+
+### Build
+
+```bash
+# Build the package.
+go build ./...
+```
+
+### Code formatting
+
+```bash
+# Format your code.
+go fmt ./...
+```
+
+### Code generation
+
+```bash
+# Make sure to update the generated code if there are any API-level changes.
+./hack/update-codegen.sh
+```
+
+```bash
+# Make sure your API and client are update-to-date.
+./hack/verify-codegen.sh
+```
+
+### Code from upstream Kubernetes
+
+Some of the code is borrowed from upstream Kubernetes, such as [controller_utils.go](https://github.com/kubernetes/kubernetes/blob/master/pkg/controller/controller_utils.go), which helps us remove the direct dependency on Kubernetes. For more background on this, please check out the discussions in [issue #48](https://github.com/kubeflow/common/issues/48). In addition, the following folders also contain some auxiliary codes to help us easily build the operators:
+
+- [control](./pkg/controller.v1/control)
+- [expectation](./pkg/controller.v1/expectation)
+
+*Note: Please don't edit these files. If you encounter any issues, please file an issue [here](https://github.com/kubeflow/common/issues).*
+
+We have a long-term plan to move them to [kubernetes/client-go](https://github.com/kubernetes/client-go). See issue [kubernetes/client-go/issues/332](https://github.com/kubernetes/client-go/issues/332) for more details.
+
+## Additional Guideline for Maintainers
+
+If you are one of the maintainers of the repo, please check out the following additional guidelines.
+
+### Commit style guide
+
+1. Please always use bot to merge PRs and never manually merge PRs.
+
+2. Release notes are generated from commits so writing good commit messages are important. Below is an example:
+
+```md
+Enhance maintainability of operator common module (#55, @Jeffwan)
+Add proposal for Prometheus metrics coverage (#77, @terrytangyuan)
+```