docs(README): add instruction on using SwaggerUI

src/adm/README.md

@@ -15,3 +15,17 @@ curl -XPOST -H "CF-Access-Client-Id: <CLIENT_ID>" -H "CF-Access-Client-Secret: <
 ```
 
 The response would attach a cookie named `CF_Authorization` that you may use for [subsequent requests](https://developers.cloudflare.com/cloudflare-one/identity/service-tokens/#subsequent-requests).
+
+## Sending request via Swagger UI
+
+You can send test requests in this Swagger UI in the browser using your current login session.
+
+However, since different APIs are managed by different Cloudflare Access Applications, your current
+login session may not yet be authorized to the API you want to call. In this case, you may see your
+request sent in Swagger UI being redirected to Cloudflare, and is then blocked by the browser.
+
+To authorize your current login session to an API, try visiting the API path directly.
+For example, in order to call `/moderation/blockUser`, you can first [visit `/moderation`](/moderation) directly in your browser.
+Cloudflare will do the authorization and redirect you to the 404 page.
+By that time your login session cookie should have been updated, and you can then call 
+`/moderation/blockUser` in `/docs`'s Swagger UI.