Add GoFirmex in who-uses

Add GoFirmex in who-uses.json

Author: amantinetti

content/discover/who-uses.json

@@ -177,6 +177,7 @@
     "https://www.kwanso.com",
     "https://cmdn.io",
     "https://ayo.so",
-    "https://devitjobs.com"
+    "https://devitjobs.com",
+    "https://gofirmex.com"
   ]
 }