Update README.md

Remove `Image_filename` dependence from description

README.md

@@ -19,17 +19,16 @@ For more information or to make your own version, see the [GitHub project repo](
 
 ## How it works
 
-For full dashboard functionality, upload a CSV or XLS file with the following columns: 
-- `Image_filename`*: Filename of each image, must be unique. **Note:** Images should be in PNG or JPEG format, TIFF may fail to render in the sample image display.
+For full dashboard functionality, upload a CSV or XLS file with the following columns:  
 - `Species`: Species of each sample.
 - `Subspecies`: Subspecies of each sample.
 - `View`: View of the sample (eg., 'ventral' or 'dorsal' for butterflies).
 - `Sex`: Sex of each sample.
-- `hybrid_stat`: Hybrid status of each sample (eg., 'valid_subspecies', 'subspecies_synonym', or 'unknown').
+- `hybrid_stat`: Hybrid status of each sample (eg., 'valid_subspecies' or 'subspecies_synonym', 'hybrid' or 'parent species').
 - `lat`*: Latitude at which image was taken or specimen was collected.
 - `lon`*: Longitude at which image was taken or specimen was collected.
-- `file_url`*: URL to access file.
+- `file_url`*: URL to access file. **Note:** Images should be in PNG or JPEG format, TIFF may fail to render in the sample image display.
 
 ***Note:** 
 - `lat` and `lon` columns are not required to utilize the dashboard, but there will be no map view if they are not included.
-- `Image_filename` and `file_url` are not required, but there will be no sample images option if either one is not included.
+- `file_url` is not required, but there will be no sample images option if it is not included.