Use "parameters" in the no-param-mutations rule

Author: erran

README.md

@@ -3413,7 +3413,7 @@ condition](#safe-assignment-in-condition).
 <sup>[[link](#functional-code)]</sup>
 
 * <a name="no-param-mutations"></a>
-  Do not mutate arguments unless that is the purpose of the method.
+  Do not mutate parameters unless that is the purpose of the method.
 <sup>[[link](#no-param-mutations)]</sup>
 
 * <a name="three-is-the-number-thou-shalt-count"></a>