big help upgrades

- short descriptions for command list
  - argument descriptions
  - render argument list on detailed help page

commands/message/google/labels.js

@@ -8,6 +8,7 @@ module.exports = {
   name: 'labels',
   metadata: {
     description: 'Applies labels to an image based on its visual contents.',
+    description_short: 'Image content label detection',
     examples: ['labels'],
     category: 'utils',
     usage: 'labels <attachment>'