chore: update ATTRIBUTION file to include Generating Units

ATTRIBUTION.md

@@ -430,6 +430,24 @@ The data are used to populate the substation topology of U.S. power grid that ca
 Public use (see https://hifld-geoplatform.opendata.arcgis.com/datasets/geoplatform::electric-substations/about). Users are advised to read the data set's metadata thoroughly to understand appropriate use and data limitations.
 
 
+##### Source
+* Name: Generating Units
+* Author: HIFLD Open
+* Description: This table represents electric power generating units associated with power plants. Generating Units are any combination of physically connected generators, reactors, boilers, combustion turbines, and other prime movers operated together to produce electric power.
+* Source: https://hifld-geoplatform.opendata.arcgis.com/
+* Exact source location: https://hifld-geoplatform.opendata.arcgis.com/datasets/geoplatform::generating-units/about
+
+##### Destination
+* Modifications to source file(s): None
+* Location: https://besciences.blob.core.windows.net/datasets/hifld/Generating_Units_Jul2020.csv
+
+##### General Purpose
+The data are used to populate a table of generating units within the contiguous U.S. that can be used to run scenarios.
+
+##### Note
+Public use (see https://hifld-geoplatform.opendata.arcgis.com/datasets/geoplatform::generating-units/about). Users are advised to read the data set's metadata thoroughly to understand appropriate use and data limitations.
+
+
 ##### Source
 * Name: Power Plants
 * Author: HIFLD Open