Updated column names in static_table

[dougrichardson]

static_table produces an error when "Generators and Scheduled Loads" is passed to table_name.

It appears the column name "Reg Cap (MW)" has changed on the Participants Excel sheet (https://www.aemo.com.au/energy-systems/electricity/national-electricity-market-nem/participate-in-the-market/registration).

This fix removes the old column name for the new one, with an additional name for Maximum Capacity.

Reproduce error:

from nemosis import static_table

static_table(
    table_name="Generators and Scheduled Loads",
    raw_data_location="/path/to/dir/"
)