Update sei_processing_order.cfg

cfg/sei_vui/sei_processing_order.cfg

 #======== SEI messages processing order ===============
-SEIPOEnabled                 : 1 			      #Enabling SEI processing order flag
+SEIPOEnabled                 : 1 			      #Enabling SEI processing order flag. In this example, it supports 5 SEI payload types.
 SEIPOPrefixFlag              : 1 0  0   0   1 
 SEIPOPayLoadType             : 4 19 142 211 4     #SEI PayloadTypes to be processed
 SEIPOProcessingOrder         : 3 2  1   0   4     #Processing order of SEI payload types