Add Mudlet (the MUD client) to Discord open source community (#169)

* Added Mudlet icon

This is B&W (well White on transparent) Minified 144x144 icon as is needed for Discord.

* Updated communites.json with Mudlet's details

communities.json

@@ -664,6 +664,13 @@
       "quote": "Discord is the perfect live chat and interaction platform for the DenizenScript team to provide support to our users and teach new programmers.",
       "inviteCode": "Q6pZGSR",
       "githubUrl": "https://github.com/DenizenScript"
+    },
+    {
+      "logo": "mudlet_icon_minified_bw.png",
+      "title": "Mudlet",
+      "quote": "Using Discord to help Users connect to 1000's of MUD Servers and Mudlet developers to connect to each other...",
+      "inviteCode": "rmFG7Wr",
+      "githubUrl": "https://github.com/Mudlet/Mudlet"
     }
   ]
 }