Add contributor guide

CONTRIBUTING.md

@@ -0,0 +1,28 @@
+# Contributing to the Pulumi ecosystem
+
+Do you want to contribute to Pulumi? Awesome! We are so happy to have you.
+We have a few tips and housekeeping items to help you get up and running.
+
+## Code of Conduct
+
+Please make sure to read and observe our [Code of Conduct](./CODE-OF-CONDUCT.md)
+
+## Community Expectations
+
+Please read about our [contribution guidelines here.](https://github.com/pulumi/pulumi/blob/master/CONTRIBUTING.md#communications)
+
+## Setting up your development environment
+
+### Pulumi prerequisites
+
+Please refer to the [main Pulumi repo](https://github.com/pulumi/pulumi/)'s [CONTRIBUTING.md file](
+https://github.com/pulumi/pulumi/blob/master/CONTRIBUTING.md#developing) for details on how to get set up with Pulumi.
+
+## Committing Generated Code
+
+You must generate and check in the SDKs on each pull request containing a code change, e.g. adding a new resource to `resources.go`.
+
+1. Run `make build_sdks` from the root of this repository
+1. Open a pull request containing all changes
+1. *Note:* If a large number of seemingly-unrelated diffs are produced by `make build_sdks` (for example, lots of changes to comments unrelated to the change you are making), ensure that the latest dependencies for the provider are installed by running `go mod tidy` in the `provider/` directory of this repository.
+