grab_historical_prices method a little misleading in description

[Wolfslayer]

python-trading-robot/pyrobot/robot.py

Line 464 in c0536b4

bar_type {str} -- Defines the bar type, can be one of the following:

        bar_type {str} -- Defines the bar type, can be one of the following:
            `['minute', 'week', 'month', 'year']` (default: {'minute'})

This is a little misleading, if I follow through to your TDClient code all the way to the TD Ameritrade documentation, there are two discrepencies:

1. aside from "minute" the rest should be in the form of "weekly" "monthly" and "yearly"

2. "daily" is also a valid option for bar width

This method is mostly utilized in your examples for streaming data by the minute so not a huge deal for that use, but I've repurposed some of this for myself for plotting candles out into the months and years hence taking a closer look into this