Add PNL to Account endpoint

Pretty straight forward: please implement the PNL endpoint to make it easier to print/log portfolio performance.

that’s great, just one thing - it has nothing to do with zipline.
it’s alpaca account data.
you should rename the title to something like: Add PNL to Account endpoint.

Done. Only mentioned zipline because the pnl enpoint was part of the zipline interface, but was not ported with everything else.