Minor errors in docs for `ledger_data`

[mvadari]

Link: https://xrpl.org/ledger_data.html

The response object appears to be a little incorrect. The example has ledger_index as a string, though the actual breakdown says "unsigned integer" and actual rippled returns an int. There is also a ledger object in result - I don't quite understand what's in that object, because rippled standalone returns something different than testnet, though both have an object there.