Added testing slack section in the README (#1116)

* Added testing slack section in the README

* Update README.md

Co-authored-by: Calvin Lu <[email protected]>

* Addressed PR Comments

---------

Co-authored-by: Hongxin <[email protected]>
Co-authored-by: Calvin Lu <[email protected]>

Author: 3 people

README.md

@@ -223,3 +223,38 @@ For more information refer to [Using Docker and Docker-Compose][], this page als
 [definitelytyped]: https://definitelytyped.org/
 [puppeteer]: https://developers.google.com/web/tools/puppeteer
 [cdp]: https://chromedevtools.github.io/devtools-protocol/
+
+## Testing Slack Integration
+
+1. Ensure you can access the MSK secret server
+2. Ensure you can access the [Slack API Manager](https://api.slack.com/apps/AQC1QUJQK/interactive-messages)
+3. Install [ngrok](https://ngrok.com/download)
+4. Update the `/src/main/resources/config/application-dev.yml` file
+
+   - Change `spring.mail.username` to [email protected]
+   - Change `spring.mail.password` to the password for [email protected] found in the secret server
+   - Change `application.slack.user-registration-webhook` to the slack hook.
+   - Change `application.slack.slack-base-url` to https://oncokb.slack.com
+   - Change `application.slack.user-registration-channel-id` to C03EASPQ8AZ
+   - If you need to use a slack endpoint that requires a token, update
+     `application.slack.slack-bot-oauth-token` with the token get from this [page](https://api.slack.com/apps/AQC1QUJQK/oauth).
+
+5. Start up ngrok
+
+   ```sh
+   ngrok http http://localhost:9090
+   ```
+
+6. Copy the forwarding URL generated by ngrok.
+
+   - Should be something like https://xxxx-xxx-xxx-xx-xx.ngrok-free.app
+
+7. Update the Request URL in the slack message configuration [in the Request URL](https://api.slack.com/apps/AQC1QUJQK/interactive-messages) to https://xxxx-xxx-xxx-xx-xx.ngrok-free.app/api/slack
+
+   - Replace the base URL with the URL generated by ngrok for forwarding
+
+8. Register an account in your local instance of OncoKB public
+
+   - Ensure the email you use is one you have access to
+
+9. Check the slack-app-dev channel for a message and approve it