Add switch for basic mode to README.

README.md

@@ -93,6 +93,7 @@ USAGE:
       -c <checknum>       specify a check number or group from the AWS CIS benchmark (i.e.: check11 for check 1.1 or check3 for entire section 3)
       -f <filterregion>   specify an AWS region to run checks against (i.e.: us-west-1)
       -m <maxitems>       specify the maximum number of items to return for long-running requests (default: 100)
+      -b                  do not use colors in the output
       -h                  this help
 
 ```