docs: add note about CAP_NET_BIND_SERVICE to readme

Author: jamaljsr

README.md

@@ -95,8 +95,13 @@ access the website from a remote computer and do not want to deal with the brows
 you about the self-signed certificate. You just need to specify the domain name you wish
 to use, and make sure port 80 is open in your in your firewall. LetsEncrypt requires this
 to verify that you own the domain name. Shushtar will listen on port 80 to handle the
-verification requests. On some linux-based platforms, you may need to run Shushtar with
-superuser privileges since port 80 is a system port.
+verification requests.
+
+On some linux-based platforms, you may need to run Shushtar with superuser privileges
+since port 80 is a system port. You can permit the
+[`CAP_NET_BIND_SERVICE`](https://www.man7.org/linux/man-pages/man7/capabilities.7.html)
+capability using `setcap 'CAP_NET_BIND_SERVICE=+eip' /path/to/shushtar` to allow binding
+on port 80 without needing to run the daemon as root.
 
 > Note: Shushtar only serves content over **HTTPS**. If you do not use `letsencrypt`,
 > Shushtar will use the self-signed certificate that is auto-generated by `lnd` to encrypt