Added Gateway description

README.md

@@ -1056,6 +1056,8 @@ Utilities for managing game servers.
 
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+A [gateway](https://en.wikipedia.org/wiki/Gateway_(telecommunications)) is a piece of networking hardware or software used in telecommunications networks that allows data to flow from one discrete network to another.
+
 - [Firezone](https://www.firezone.dev/) - Self-hosted secure remote access gateway that supports the WireGuard protocol. It offers a Web GUI, 1-line install script, multi-factor auth (MFA), and SSO. ([Source Code](https://github.com/firezone/firezone)) `Apache-2.0` `Elixir`
 - [Guacamole](https://guacamole.apache.org) - Guacamole is a clientless remote desktop gateway. It supports standard protocols like VNC and RDP. ([Source Code](https://github.com/glyptodon/)) `Apache-2.0` `Java/C`
 - [ShellHub](https://www.shellhub.io) - ShellHub is a modern SSH server for remotely accessing linux devices via command line (using any SSH client) or web-based user interface, designed as an alternative to sshd. ([Source Code](https://github.com/shellhub-io/shellhub)) `Apache-2.0` `Go/Other`