fixing minor text in example

Author: howcom

css3-multicol/Overview.src.html

@@ -138,7 +138,9 @@ <h2>Introduction</h2>
 or both, properties in one declaration.
 
 <div class=example>
-<p>In this example, both the number and widths of columns is set:
+
+<p>In these examples, the number of columes, the width of columns, and
+both the number and widths are set:
 
 <pre>
 body { columns: 2 }