touch a word about e2e tests in readme

README.md

@@ -303,8 +303,20 @@ To develop a new action or improve an existing one, check the ["Actions" doc](sr
 
 ## Testing
 
+### Unit tests
+
 Execute `npm test` to run static analysis checks and the test suite. Requires Docker to run integration tests against a CouchDB instance. 
 
+### End-to-end tests
+
+Run `npm run e2e-test` to run the end-to-end test suite against an actual CHT instance locally.
+These tests rely on [CHT Docker Helper](https://docs.communityhealthtoolkit.org/hosting/4.x/app-developer/#cht-docker-helper-for-4x)
+to spin up and tear down an instance locally.
+
+The code interfacing with CHT Docker Helper lives in [`test/e2e/cht-docker-utils.js`](./test/e2e/cht-docker-utils.js).
+You should rely on the API exposed by this file to orchestrate CHT instances for testing purposes.
+It is preferable to keep the number of CHT instances orchestrated in E2E tests low as it takes a non-negligible amount of time to spin up an instance and can quickly lead to timeouts.
+
 ## Executing your local branch
 
 1. Clone the project locally