donchian_channel: Add Donchian Channels
to the chart
Description
A high-level plotly::add_lines()-wrapper function that interacts
with the TTR::DonchianChannel()-function.
The function adds Donchian Channels
to the main chart().
Usage
donchian_channel(
n = 10,
include.lag = FALSE,
color = '#4682b4',
...
)