Add Qubes OS to list of operating systems.

README.md

@@ -722,6 +722,7 @@ performance of any of your sites from across the globe.<br>
 &nbsp;&nbsp;:small_orange_diamond: <a href="https://securityonion.net/"><b>Security Onion</b></a> - Linux distro for intrusion detection, enterprise security monitoring, and log management.<br>
 &nbsp;&nbsp;:small_orange_diamond: <a href="https://tails.boum.org/"><b>Tails</b></a> - is a live system that aims to preserve your privacy and anonymity.<br>
 &nbsp;&nbsp;:small_orange_diamond: <a href="https://github.com/vedetta-com/vedetta"><b>vedetta</b></a> - OpenBSD router boilerplate.<br>
+&nbsp;&nbsp;:small_orange_diamond: <a href="https://www.qubes-os.org"><b>Qubes OS</b></a> - is a security-oriented OS that uses Xen-based virtualization to create and manage isolated compartments called qubes.<br>
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 ##### :black_small_square: HTTP(s) Services