Checklist

• I have used the search function to see if someone else has already submitted the same feature request.
• I will only create one feature request per issue.
• I will describe the problem with as much detail as possible.

System info

App version: 2.1.1

App source: Google Play

Enhancement description

Problem you may be having, or feature you want: the Episode cache linked to the automatic downloads is useful, but can lead to confusion, as is clear from this conversation on Twitter. We should better guide users in this, and make the feature easier to understand.

Suggested solution:

• Rename 'episode cache' to 'Episode storage limit' or 'Episode download limit' (or something like that). 'Cache' is used for two different things in the app, and a rather technical term.
• Show a pop-up to the user when the episode limit is reached for the first time. (Or do we already do this?). The pop-up text showing after hitting the icon in the menu should get the same text. It should read something like:
  Episode storage limit reached
  AntennaPod has download the maximum number of episodes on your device. In the settings you can:
  • increase the limit (under Automatic Download)
  • enable Episode Cleanup (under Automatic Download)
  • enable Auto Delete (under Storage)
• Make the episode limit universal - i.e. not only for automatic but also manual downloads. It could work in a similar fashion as downloading over mobile network, i.e. show a warning when the maximum is reached and let user override when downloading manually.
• Move the episode limit setting under 'Storage', or (if the above isn't implemented) add there a reference to the setting. Storage is where I first checked when replying on Twitter; it's hard to find it currently (even though it makes sense it is under Automatic Downloads).

Related to #2990