nwtc not defined

`nwtc` not defined. SHould be `lat_lon`

Author: ssolson

US_Wave.md

@@ -139,7 +139,7 @@ from rex import ResourceX
 wave_file = '/nrel/US_wave/West_Coast/West_Coast_wave_2010.h5'
 lat_lon = (34.399408, -119.841181)
 with ResourceX(wave_file, hsds=True) as f:
-    lat_lon_swh = f.get_lat_lon_df('significant_wave_height', nwtc)
+    lat_lon_swh = f.get_lat_lon_df('significant_wave_height', lat_lon)
 ```
 
 or to extract all sites in a given region: