Fix image path in external-auth.mdx and add the image to apps directory

Author: dannyroosevelt

docs-v2/pages/apps/external-auth.mdx

@@ -19,7 +19,7 @@ Passing external credentials at runtime is a feature that's available to custome
 2. From your app, retrieve credentials and send them in an HTTP request to the endpoint with the rest of the payload.
 3. In the step of your workflow where you'd like to pass these credentials, select the **Use external authentication** option at the bottom-right of the account selector:
 
-![Select "External Auth"](/images/apps/select-external-auth.png)
+![Select "External Auth"](/images/integrations/select-external-auth.png)
 
 4. You'll be prompted for all required credentials for the app, often just an `oauth_access_token` or `api_key`. [Find the variable that contains your credentials](/workflows/building-workflows/triggers/#copying-references-to-event-data) and pass them to each field:
 
@@ -42,7 +42,7 @@ You can set [the `pd-nostore` flag](/workflows/building-workflows/triggers/#x-pd
 1. Add a step to your workflow to fetch credentials from your DB or secrets store.
 2. In the step of your workflow where you'd like to pass these credentials, select the **Use external authentication** option at the bottom-right of the account selector:
 
-![Select "External Auth"](/images/apps/select-external-auth.png)
+![Select "External Auth"](/images/integrations/select-external-auth.png)
 
 3. You'll be prompted for all required credentials for the app, often just an `oauth_access_token` or `api_key`. [Find the variable that contains your credentials](/workflows/building-workflows/triggers/#copying-references-to-event-data) and pass them to each field: