[real-world uses] Add Violentmonkey

Author: orionlee

doc/realworld.html

@@ -182,6 +182,7 @@ <h2>CodeMirror real-world uses</h2>
       <li><a href="http://turbopy.com/">TurboPY</a> (web publishing framework)</li>
       <li><a href="http://cruise.eecs.uottawa.ca/umpleonline/">UmpleOnline</a> (model-oriented programming tool)</li>
       <li><a href="https://upsource.jetbrains.com/idea-ce/file/idea-ce-7706e7832aa9e2fd0c2decdb5cbef2225692c696/platform/platform-impl/src/com/intellij/openapi/editor/impl/EditorFactoryImpl.java">Upsource</a> (code browser and review tool)</li>
+      <li><a href="https://violentmonkey.github.io/">Violentmonkey</a> (userscript manager / editor)</li>
       <li><a href="https://github.com/mgaitan/waliki">Waliki</a> (wiki engine)</li>
       <li><a href="http://wamer.net/">Wamer</a> (web application builder)</li>
       <li><a href="https://github.com/brettz9/webappfind">webappfind</a> (windows file bindings for webapps)</li>