doc: add support doc

Author: andyzhangx

support.md

@@ -0,0 +1,16 @@
+# Support
+
+## How to file issues and get help
+
+This project uses GitHub Issues to track bugs and feature requests. Please search the [existing issues][github-issues] before filing new issues to avoid duplicates. For new issues, file your bug or feature request as a new Issue.
+
+For help and questions about using this project, please:
+
+  - Read the [documentation][docs]
+  - Join us on the [#sig-storage][sig-storage-slack] Slack channel
+
+This project maintainers will respond to the best of their abilities.
+
+[sig-storage-slack]: https://kubernetes.slack.com/archives/C09QZFCE5
+[docs]: https://github.com/kubernetes-csi/csi-driver-nfs/tree/master/docs
+[github-issues]: https://github.com/kubernetes-csi/csi-driver-nfs/issues