Issue #511 Copying Docs from DefValidator (#518)

DefaultValidator has method documentation, so I'm just copying the
contents verbatim to the interface.

Quick win.

Author: jeremiahjstacey

src/main/java/org/owasp/esapi/Validator.java

@@ -48,8 +48,14 @@
  */
 public interface Validator {
 
+	/**
+	 * Add a validation rule to the registry using the "type name" of the rule as the key.
+	 */
 	void addRule( ValidationRule rule );
 
+	/**
+	 * Get a validation rule from the registry with the "type name" of the rule as the key.
+	 */
 	ValidationRule getRule( String name );
 
 	/**