NOX Index has a baseline of 1 for Sensirion (only known usage)

[tyeth]

The code comment clearly states the NOX index is using a baseline value of 100, like the VOC Index, but the NOX index has a baseline value of 1 according to the Sensirion documentation

Adafruit_Sensor/Adafruit_Sensor.h

Line 154 in 7b2473b

float nox_index; /**< NOx (Nitrogen Oxides) index where 100 is normal

Docs:
SGP40 gas index algorithm repo + docs mentioning baselines of VOC 100 and NOX 1:
https://github.com/Sensirion/gas-index-algorithm/blob/b70ae926519fe66d5f8f8620f3250d1a376b8b22/python-wrapper/sensirion_gas_index_algorithm/gas_index_algorithm.py#L58C99-L58C108

NOX Index Specific documentation:
https://sensirion.com/media/documents/9F289B95/6294DFFC/Info_Note_NOx_Index.pdf