[css-values] typo

--HG--
extra : rebase_source : efc5750e774d222cbc5cf05f30507edc16d479c1

Author: tabatkins

css-values/Overview.html

@@ -1425,7 +1425,7 @@ <h2 id=functional-notation><span class=secno>8. </span> Functional
   <p> Some legacy functional notations, such as ‘<code
    class=css>rgba()</code>’, use commas unnecessarily, but generally commas
    are only used to separate items in a list, or pieces of a grammar that
-   would be ambiguous otherwise. If a comma is used to separate argument,
+   would be ambiguous otherwise. If a comma is used to separate arguments,
    whitespace is optional before and after the comma.
 
   <pre class=example>

css-values/Overview.src.html

@@ -955,7 +955,7 @@ <h2 id="functional-notation">
 		Some legacy functional notations, such as ''rgba()'', use commas unnecessarily,
 		but generally commas are only used to separate items in a list,
 		or pieces of a grammar that would be ambiguous otherwise.
-		If a comma is used to separate argument,
+		If a comma is used to separate arguments,
 		whitespace is optional before and after the comma.
 
 	<pre class="example">