[Console] Print command description in help output

`list` will show the command descriptions:

```
Available commands:
  add   Save a command
  help  Displays help for a command
  list  Lists commands
```

However `help add` won't show the description:

```
Usage:
  add <shortcut> <cmd> [<desc>]
...
```

I'd suggest the following, at least as an option:

```
Save a command

Usage:
  add <shortcut> <cmd> [<desc>]
...
```
