add contributing doc

CONTRIBUTING.md

@@ -0,0 +1,14 @@
+# Contributing
+
+This project welcomes contributions and suggestions. Most contributions require you to
+agree to a Contributor License Agreement (CLA) declaring that you have the right to,
+and actually do, grant us the rights to use your contribution. For details, visit
+[https://cla.microsoft.com](https://cla.microsoft.com).
+
+When you submit a pull request, a CLA-bot will automatically determine whether you need
+to provide a CLA and decorate the PR appropriately (e.g., label, comment). Simply follow the
+instructions provided by the bot. You will only need to do this once across all repositories using our CLA.
+
+This project has adopted the [Microsoft Open Source Code of Conduct](https://opensource.microsoft.com/codeofconduct/).
+For more information see the [Code of Conduct FAQ](https://opensource.microsoft.com/codeofconduct/faq/)
+or contact [opencode@microsoft.com](mailto:opencode@microsoft.com) with any additional questions or comments.

README.md

@@ -121,6 +121,30 @@ There are many advanced concepts in COM that our library aim to support. Relevan
 
 [docs]: https://github.com/microsoft/com-rs/tree/master/docs
 
+## Contributing
+
+## Building
+
+This library is Windows only, so the easiest way to contribute will be on a Windows machine. You can execute the examples like so:
+
+```powershell
+cd examples\basic
+cargo run --release
+```
+
+If you are on a Mac or Linux machine, you should still be able to make changes and check that they compile by running the following from the root of the project:
+
+```bash
+cargo check --target=x86_64-pc-windows-msvc
+```
+
+For more information on contributing, take a look at the [contributing doc](./CONTRIBUTING.md)
+
+### Code of Conduct
+
+This project has adopted the [Microsoft Open Source Code of Conduct](https://opensource.microsoft.com/codeofconduct). You can find out more in the [code of conduct doc](./CODE_OF_CONDUCT.md).
+
+
 ## FAQ
 
 **Is there IDL support?**