btcli root list-delegates help: implies the ability to filter by wallet, yet not an option

[dougsillars]

in the docs:
$ btcli root list_delegates --wallet-name my_wallet

but --wallet-name is not listed as an option under Options, and attempting to use it leads to the error:

No such option: --wallet-name

Expected: if the example is in the docs, it should work. IF it does not work - remove from the docs until it does.

[thewhaleking]

Closed by #139