docs: change API key to secret for Rootly

Author: tnolet

site/content/docs/integrations/rootly.md

@@ -13,7 +13,7 @@ Checkly integrates with [Rootly](https://rootly.com/) to monitor your alerts and
 1. Log in to Rootly and navigate to **Alerts > Alert Sources**, click **Add Alert Source** and select "Checkly"."
 
 2. Take note of the following:
-   - The **API key** that Rootly.io provides you with.
+   - The **Secret** that Rootly.io provides you with.
    - The **type** you want to target: either **Service**, **Group** or **Escalation Policy**.
    - The **ID** of the target.
   Now head over to [Checkly > Alerts](https://app.checklyhq.com/alerts/settings), click **Add more channels** and select **Rootly**.