README.md: add packages and API request notes

Author: Sergey Khomushin

README.md

@@ -7,7 +7,9 @@ Use you EmailJS account for sending emails.
 ## Disclaimer
 
 This is a flutter-only version, otherwise use
-the [REST API](https://www.emailjs.com/docs/rest-api/send/).
+- [Browser SDK](https://www.npmjs.com/package/@emailjs/browser)
+- [Node.js SDK](https://www.npmjs.com/package/@emailjs/nodejs)
+- [REST API](https://www.emailjs.com/docs/rest-api/send/)
 
 ## Links
 
@@ -28,6 +30,15 @@ Install EmailJS SDK:
 $ flutter pub add emailjs 
 ```
 
+***Note***: By default, API requests are disabled for non-browser applications.
+You need to activate them through [Account:Security](https://dashboard.emailjs.com/admin/account/security).
+
+## FAQ
+
+#### API calls are disabled for non-browser applications
+You need to activate API requests
+through [Account:Security](https://dashboard.emailjs.com/admin/account/security).
+
 ## Examples
 
 **send email**