Investigate & document "freebie" trust lines

[mDuo13]

Supposedly, it is possible for a user to have up to 2 trust lines without needing to pay the reserve.

https://github.com/ripple/rippled/blob/866425738194a4dda2d142dfc7e73cdea71d526d/src/ripple/app/tx/impl/SetTrust.cpp#L153-L167

Investigate and update the Reserves page with the exceptions.