Add usage documentation for count-offenses

Author: davidstosik

USAGE.md

@@ -20,6 +20,7 @@
   * [Understanding how to respond to new violations](#understanding-how-to-respond-to-new-violations)
 * [Recording existing violations](#recording-existing-violations)
   * [Understanding the package todo file](#understanding-the-package-todo-file)
+* [Counting offenses](#counting-offenses)
 * [Loading extensions](#loading-extensions)
 
 ## What problem does Packwerk solve?
@@ -239,6 +240,15 @@ Above is an example of a constant violation entry in `package_todo.yml`.
 
 Violations exist within the package that makes a violating reference.
 
+
+# Counting Offenses
+
+You can generate a count of all offenses by running:
+
+    bin/packwerk count-offensess
+
+This will output a list of packages with their respective offense count.
+
 # Loading Extensions
 
 You can optionally specify ruby files that you'd like to be loaded with `packwerk` by specifying a `require` directive in `packwerk.yml`:

lib/packwerk/cli.rb

@@ -120,6 +120,7 @@ def usage
         Subcommands:
           init - set up packwerk
           check - run all checks
+          count-offenses - displays an offense count per package
           update-todo - update package_todo.yml files
           validate - verify integrity of packwerk and package configuration
           version - output packwerk version