Updated descriptions

public/v2/apps/mongo-express.json

@@ -1,7 +1,7 @@
 {
     "captainVersion": "2",
     "documentation": "Taken from https://hub.docker.com/_/mongo-express/ except it is manually adjusted for port 80",
-    "description": "",
+    "description": "Web-based MongoDB admin interface, written with Node.js and express",
     "dockerCompose": {
         "version": "3.3",
         "services": {