fix typos in doc
fix typos in doc

stuart-thackray/nitrogen,nitrogen/nitrogen,stuart-thackray/nitrogen,nitrogen/nitrogen,kevinmontuori/nitrogen,nitrogen/nitrogen,joaohf/nitrogen,choptastic/nitrogen,joaohf/nitrogen,stuart-thackray/nitrogen,choptastic/nitrogen,joaohf/nitrogen,kevinmontuori/nitrogen,kevinmontuori/nitrogen,choptastic/nitrogen