[real-world uses] Add salvare

Author: szekelymilan

doc/realworld.html

@@ -144,6 +144,7 @@ <h2>CodeMirror real-world uses</h2>
       <li><a href="http://refork.com/">Refork</a> (animation demo gallery and sharing)</li>
       <li><a href="http://sagecell.sagemath.org">SageMathCell</a> (interactive mathematical software)</li>
       <li><a href="https://cloud.sagemath.com/">SageMathCloud</a> (interactive mathematical software environment)</li>
+      <li><a href="https://github.com/szekelymilan/salvare">salvare</a> (real-time collaborative code editor)</li>
       <li><a href="https://chrome.google.com/webstore/detail/servephp/mnpikomdchjhkhbhmbboehfdjkobbfpo">ServePHP</a> (PHP code testing in Chrome dev tools)</li>
       <li><a href="http://scala-lang.org/blog/2017/02/20/introducing-scastie.html">Scastie</a> (Scala playground)</li>
       <li><a href="https://www.shadertoy.com/">Shadertoy</a> (shader sharing)</li>