Correct help text per timg236's comments

rpi-eeprom-config

@@ -97,10 +97,23 @@ class BootloaderImage(object):
                 sys.stdout.write(config_bytes)
 
 def main():
-    parser = argparse.ArgumentParser('RPI EEPROM config tool')
-    parser.add_argument('--config', help='Insert new bootloader config into EEPROM image. CONFIG specifies the file containing the new config.')
-    parser.add_argument('--out', help='Extract current bootloader config from EEPROM image. OUT specifies the file to put the config into.')
-    parser.add_argument('eeprom', help='Name of EEPROM image file (e.g. pieeprom.bin)')
+    parser = argparse.ArgumentParser(formatter_class=argparse.RawDescriptionHelpFormatter, \
+    description='RPI EEPROM config tool. \
+\n\nThere are 3 operating modes: \
+\n\n1. Output the bootloader configuration stored in an EEPROM image file to \
+the screen (STDOUT): specify only the name of an EEPROM image file using the \
+EEPROM option. \
+\n\n2. Output the bootloader configuration stored in an EEPROM image file to a \
+file: specify the EEPROM image file using the EEPROM option, and the output file\
+using the --out option. \
+\n\n3. Insert a new bootloader configuration into an EEPROM image file: specify \
+the EEPROM image file using the EEPROM option, the bootloader configuration file\
+using the --config option, and the name to use for the new file which will be a \
+combination of the original EEPROM image file, along with the new bootloader \
+configuration.')
+    parser.add_argument('--config', help='Filename of new bootloader config')
+    parser.add_argument('--out', help='Name of output file')
+    parser.add_argument('EEPROM', help='EEPROM filename (pieeprom.bin)')
     args = parser.parse_args()
 
     image = BootloaderImage(args.eeprom, args.out)
@@ -110,4 +123,4 @@ def main():
         image.read()
 
 if __name__ == '__main__':
-    main()
+    main()