fixes typo

README.md

@@ -9,9 +9,49 @@
 
 ## Writing a test suite
 
-- Update docker-compose.yaml
-- Develop test suite with webdriver.io
-- Connect
+- Add your services to `docker-compose.yaml`
+- Write some journey tests using [webdriver.io](https://webdriver.io/docs/gettingstarted)
+- Configure `wdio.conf.js` to point at the service you want to test.
+- Run your tests, by either:
+  - Running the [Journey Tests Workflow](https://github.com/DEFRA/cdp-node-journey-test-template/actions/workflows/run-tests.yaml) manually via Github actions
+  - Add calls to the [Journey Tests Workflow](https://github.com/DEFRA/cdp-node-journey-test-template/blob/main/.github/workflows/run-tests.yaml) to the service repositories covered by the test suite
+
+### Updating docker-compose.yaml
+
+The base docker-compose.yaml has an example service as well as some supporting infrastructure. These can be removed if not required.
+All services built on the platform publish to DEFRA's dockerhub [https://github.com/DEFRA/](https://github.com/DEFRA/), you should use these images for testing as they're the same ones that will be deployed.
+
+Service configuration should be done via environment variables, as it is in the real environments.
+
+### Docker networking considerations
+
+By default, docker compose will use bridged networking, meaning each container gets its own hostname/ip. Services should be configured to talk to each other using these hostnames.
+
+A service can also expose specific ports to the host using the `ports` configuration. Typically, you'd do this for the frontend service you're testing.
+
+You can consider using `host` networking mode, where all services appear on localhost, though this may be harder to develop if you're using Docker Desktop on Macs or Windows.
+
+### How to trigger the test suite when a related service is built
+
+You can use the `run-tests.yaml` workflow from this project as a reusable workflow to be called as a step in another workflow in another project.
+
+The easiest way to do this is to cut and paste the following into `.github/workflows/journey-tests.yaml` in the github repository you want to run the test from:
+
+```yaml
+name: Jouney Tests
+
+on:
+  workflow_dispatch:
+  workflow_run:
+    workflows: ['Publish']
+    types:
+      - completed
+jobs:
+  test:
+    uses: defra/cdp-node-journey-test-template/.github/workflows/run-tests.yaml@main
+```
+
+This can be done for any number of services covered by your test suite, allowing for it to be run whenever any of those services publish a new version.
 
 ## Licence