docs: Convert slack links to CNCF, add link to contributing guide (#40)

**What changed?**

Converts links from our old slack instance to the CNCF community
inviter.
Adds a link to our shared contributing guide to the contributing readme.

**Why?**

The goal of the contribution guide is to move all common guides and
processes between our repositories to a shared place – reducing
conflicting information and streamlining the process to contribute to
cadence.

**How did you test it?**

N/A

Potential risks

N/A

Release notes

N/A

Documentation Changes

N/A

Author: vishwa-uber

CONTRIBUTING.md

@@ -0,0 +1,31 @@
+# Contributing to Cadence Python Client
+
+This doc is intended for contributors to the Cadence Python Client. 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 Python client 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/cadence-workflow/cadence-python-client/labels/good%20first%20issue).
+These issues are a great way to start contributing to Cadence Python Client.
+
+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.
+
+## Submitting Pull Requests
+
+1. Fork the repository
+2. Create a feature branch from `main`
+3. Make your changes following the code quality guidelines above
+4. Write or update tests as needed
+5. Ensure all tests pass and there are no linting/type errors
+6. Submit a pull request with a clear description of your changes
+
+## Getting Help
+
+- **GitHub Issues**: [Report bugs or request features](https://github.com/cadence-workflow/cadence-python-client/issues/new)
+- **CNCF Slack**: Join the **#cadence-users** channel at [cloud-native.slack.com](https://communityinviter.com/apps/cloud-native/cncf)
+- **Stack Overflow**: Tag questions with `cadence-workflow`
+
+## License
+
+By contributing to Cadence Python Client, you agree that your contributions will be licensed under the Apache 2.0 License.
+

README.md

@@ -2,6 +2,8 @@
 
 [Cadence](https://github.com/uber/cadence) is a distributed, scalable, durable, and highly available orchestration engine we developed at Uber Engineering to execute asynchronous long-running business logic in a scalable and resilient way.
 
+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.
+
 `cadence-python-client` is the Python framework for authoring workflows and activities.
 
 ## Disclaimer