docs: add _some_ details to CONTRIBUTING.md (#500)

Author: Silas Boyd-Wickizer

CONTRIBUTING.md

@@ -2,7 +2,43 @@
 
 Thanks for taking the time to contribute!
 
-## Publishing a new release
+## Contributing an Issue
 
-If you're a maintainer use `npm run release` to start the release
-process and follow the instructions printed to the console.
+We will try to respond to every issue. The issues that get the
+quickest response are the ones that are easiest to respond to. The
+issues that are easiest to respond to usually include the
+following:
+
+* For unexpected behavior or bugs, include sufficient details about
+  your cluster and workload so that other contributors can try to
+  reproduce the issue.
+* For requests for help, explain what outcome you're trying to achieve
+  (*e.g.*, "access secret data in AWS Secret Manager from a `Pod`")
+  in addition to how you're trying to achieve it (*e.g.*, "I installed
+  the Helm Chart on my cluster with these options and created an
+  `ExternalSecret`").
+* Relevant logs (*e.g.*, warnings and errors) from the external
+  secrets controller.
+* For feature requests, a description of the impact the feature will
+  have on your project or cluster management experience. If possible,
+  include a link to the open source repository for your project.
+
+## Contributing a Pull Request
+
+The most useful PRs provide the following:
+
+1. Rationale for the PR. This can be a link to a supporting issue, or
+   if it's a short PR a brief explanation in the PR.
+1. Changes that pass all testing (*i.e.*, your PR will not break
+   main). See the Development section in the
+   [README.md](./README.md#development) for more details.
+1. A small set of changes. It's OK to split up the full implementation
+   of a large new feature over multiple PRs that each add a small bit
+   of functionality.
+
+## Maintainers
+
+### Publishing a new release
+
+Use `npm run release` to start the release process and follow the
+instructions printed to the console.