[Feature Request] Ability to set custom description

[alexandrevicenzi]

Right now ES can only show "X GAMES AVAILABLE" description. It would be nice to have a custom message as for example "X PORTS AVAILABLE", "X APPS AVAILABLE" or anything else.

With a few changes in SystemView and SystemData this can be done. My suggestion is to add a new optional tag to the xml cfg file, like:

<description>
  <singular>Game Available</singular>
  <plural>Games Available</plural>
</description>

I would be happy to send a PR for this change.