Help output now shows available doc generators (ref #776)

Author: gsherwood

CodeSniffer/CLI.php

@@ -1176,8 +1176,8 @@ public function printPHPCSUsage()
         echo '                      (extension filtering only valid when checking a directory)'.PHP_EOL;
         echo '                      The type of the file can be specified using: ext/type'.PHP_EOL;
         echo '                      e.g., module/php,es/js'.PHP_EOL;
-        echo '        <generator>   The name of a doc generator to use'.PHP_EOL;
-        echo '                      (forces doc generation instead of checking)'.PHP_EOL;
+        echo '        <generator>   Uses either the "HMTL", "Markdown" or "Text" generator'.PHP_EOL;
+        echo '                      (forces documentation generation instead of checking)'.PHP_EOL;
         echo '        <patterns>    A comma separated list of patterns to ignore files and directories'.PHP_EOL;
         echo '        <report>      Print either the "full", "xml", "checkstyle", "csv"'.PHP_EOL;
         echo '                      "json", "emacs", "source", "summary", "diff"'.PHP_EOL;