Imports data from NWIS about measured parameter based on user-supplied parameter code or codes. This function gets the data from here: https://nwis.waterdata.usgs.gov/nwis/pmcodes
Value
parameterData data frame with the following information:
| Name | Type | Description | 
| parameter_cd | character | 5-digit USGS parameter code | 
| parameter_group_nm | character | USGS parameter group name | 
| parameter_nm | character | USGS parameter name | 
| casrn | character | Chemical Abstracts Service (CAS) Registry Number | 
| srsname | character | Substance Registry Services Name | 
| parameter_units | character | Parameter units | 
