docs: Convert slack links to CNCF, add link to contributing guide

Author: vishwa-uber

CONTRIBUTING.md

@@ -2,9 +2,11 @@
 
 This doc is intended for contributors to `cadence-java-client` (hopefully that's you!)
 
-For general information about contributing to Cadence projects, please see our [shared contributing guide](https://github.com/cadence-workflow/.github/blob/main/CONTRIBUTING.md).
+📚 **New to contributing to Cadence?** Check out our [Contributing Guide](https://cadenceworkflow.io/community/how-to-contribute/getting-started) for an overview of the contribution process across all Cadence repositories. This document contains cadence-java-client specific setup and development instructions.
 
-**Note:** All contributors also need to fill out the [Uber Contributor License Agreement](http://t.uber.com/cla) before we can merge in any of your changes
+**Note:** All contributors also need to fill out the [Uber Contributor License Agreement](http://t.uber.com/cla) before we can merge in any of your changes.
+
+Join our community on the CNCF Slack workspace at [cloud-native.slack.com](https://communityinviter.com/apps/cloud-native/cncf) in the **#cadence-users** channel to reach out and discuss issues with the team.
 
 ## Development Environment
 

README.md

@@ -44,10 +44,16 @@ The documentation on how to use the Cadence Java client is [here](https://cadenc
 
 Javadocs for the client API are located [here](https://www.javadoc.io/doc/com.uber.cadence/cadence-client).
 
+## Community
+
+Join our community on the CNCF Slack workspace at [cloud-native.slack.com](https://communityinviter.com/apps/cloud-native/cncf) in the **#cadence-users** channel for discussions, questions, and support.
+
 [![Slack Status](https://img.shields.io/badge/slack-join_chat-white.svg?logo=slack&style=social)](https://communityinviter.com/apps/cloud-native/cncf)
 
 ## Contributing
 We'd love your help in making the Cadence Java client great. Please review our [contribution guidelines](CONTRIBUTING.md).
 
+If you'd like to propose a new feature, first join the [CNCF Slack workspace](https://communityinviter.com/apps/cloud-native/cncf) in the **#cadence-users** channel to start a discussion.
+
 ## License
 Apache 2.0 License, please see [LICENSE](LICENSE) for details.