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

CONTRIBUTING.md

@@ -0,0 +1,44 @@
+# Contributing to Cadence Samples
+
+This doc is intended for contributors to Cadence samples. Thanks for considering to contribute ❤️
+
+> 📚 **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-samples specific setup and development instructions.
+
+Once you go through the rest of this doc and get familiar with local development setup, take a look at the list of issues labeled with
+[good first issue](https://github.com/uber-common/cadence-samples/labels/good%20first%20issue).
+These issues are a great way to start contributing to Cadence samples. Later when you are more familiar with Cadence, look at issues with
+[help wanted](https://github.com/uber-common/cadence-samples/labels/help%20wanted).
+
+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.
+
+### Documentation
+
+- Every sample must have a README.md
+- Include:
+  - What the sample demonstrates
+  - Real-world use cases
+  - How to run the sample
+  - Expected output
+  - Key concepts
+
+### Getting Help
+
+If you need help or have questions:
+
+- Join [CNCF Slack #cadence-users](https://communityinviter.com/apps/cloud-native/cncf)
+- Ask on [StackOverflow](https://stackoverflow.com/questions/tagged/cadence-workflow) with tag `cadence-workflow`
+- Open a [GitHub Discussion](https://github.com/uber-common/cadence-samples/discussions)
+- File an [issue](https://github.com/uber-common/cadence-samples/issues) for bugs
+
+## Code of Conduct
+
+Please be respectful and constructive in all interactions. We're all here to learn and help each other build better software.
+
+## License
+
+By contributing, you agree that your contributions will be licensed under the Apache 2.0 License.
+
+---
+
+Thank you for contributing to Cadence samples! Your efforts help the entire community. 🚀
+

README.md

@@ -15,6 +15,7 @@ Learn more about Cadence at:
 - [Documentation](https://cadenceworkflow.io)
 - [Cadence Server](https://github.com/cadence-workflow/cadence)
 - [Cadence Go Client](https://github.com/cadence-workflow/cadence-go-client)
+- [CNCF Slack](https://communityinviter.com/apps/cloud-native/cncf) - Join **#cadence-users** channel on CNCF Slack
 
 ## 🚀 Quick Start