chore(README): add contributing section to readme (#13059)

README.md

@@ -116,3 +116,9 @@ We are always working on new integrations. Feel free to open an issue to request
 
 - [**Provision Coder with Terraform**](https://github.com/ElliotG/coder-oss-tf): Provision Coder on Google GKE, Azure AKS, AWS EKS, DigitalOcean DOKS, IBMCloud K8s, OVHCloud K8s, and Scaleway K8s Kapsule with Terraform
 - [**Coder Template GitHub Action**](https://github.com/marketplace/actions/update-coder-template): A GitHub Action that updates Coder templates
+
+## Contributing
+
+We are always happy to see new contributors to Coder. If you are new to the Coder codebase, we have
+[a guide on how to get started](https://coder.com/docs/v2/latest/CONTRIBUTING). We'd love to see your
+contributions!