Update README w/ new append_rules module support

README.md

@@ -125,7 +125,7 @@ Optional parameters:
 | -r, --regions | regions | [REGIONS [REGIONS ...]], ALL_REGIONS  | Test the template against many regions.  [Supported regions](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/cfn-resource-specification.html) |
 | -b, --ignore-bad-template | ignore_bad_template | | Ignores bad template errors |
 | --ignore-templates | IGNORE_TEMPLATES [IGNORE_TEMPLATES ...] | Ignore templates from being scanned
-| -a, --append-rules | append_rules | [RULESDIR [RULESDIR ...]] | Specify one or more rules directories using one or more --append-rules arguments. |
+| -a, --append-rules | append_rules | [RULESPATH [RULESPATH ...]] | Specify one or more rules paths using one or more --append-rules arguments.  Each path can be either a directory containing python files, or an import path to a module. |
 | -i, --ignore-checks | ignore_checks | [IGNORE_CHECKS [IGNORE_CHECKS ...]] | Only check rules whose ID do not match or prefix these values.  Examples: <br />- A value of `W` will disable all warnings<br />- `W2` disables all Warnings for Parameter rules.<br />- `W2001` will disable rule `W2001` |
 | -e, --include-experimental | include_experimental | | Whether rules that still in an experimental state should be included in the checks |
 | -c, --include-checks | INCLUDE_CHECKS [INCLUDE_CHECKS ...] | Include rules whose id match these values