Show & explain reserved channel funds to users

[wbobeirne]

Description of the Feature or Idea

I frequently get asked about why a user's local capacity + remote capacity != channel capacity. We currently don't do anything to show or explain the amount a user has withheld in the channel reserves. This would also be a good opportunity to teach them about it with a tooltip of sorts.

[johncantrell97]

Do you think we should handle this by exposing and explaining the commitment tx fees to the user? Should we update the total capacity number we show to reflect the true capacity to not include these fees and reserves?
Or do you just want a tooltip on the capacity metric to explain the difference?