update README

Author: obiot

README.md

@@ -46,5 +46,5 @@ Questions, need help ?
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 If you need technical support, you can contact us through the following channels :
 * Forums: with melonJS 2 we moved to a new discourse [forum](https://melonjs.discourse.group), but we can still also find the previous one [here](http://www.html5gamedevs.com/forum/32-melonjs/)
-* Chat: come and chat with us on [discord](https://discord.gg/aur7JMk), or [gitter](https://gitter.im/melonjs/public)
+* Chat: come and chat with us on [discord](https://discord.gg/aur7JMk)
 * we tried to keep our [wikipage](https://github.com/melonjs/melonJS/wiki) up-to-date with useful links, tutorials, and anything related melonJS.