Added note to vw/vh about paged media changing the ICB.

Author: tabatkins

css3-values/Overview.html

@@ -1004,6 +1004,10 @@ <h4 id=viewport-relative-lengths><span class=secno>5.1.2. </span>
     <p class=issue>Do we need this now that we have the min() function?
   </dl>
 
+  <p class=note>Note that Paged Media defines how the initial containing
+   block transforms across varying page widths. This also affects these
+   units.
+
   <h3 id=absolute-lengths><span class=secno>5.2. </span> Absolute lengths:
    the &lsquo;<code class=css>cm</code>&rsquo;, &lsquo;<code
    class=css>mm</code>&rsquo;, &lsquo;<code class=css>in</code>&rsquo;,

css3-values/Overview.src.html

@@ -610,6 +610,9 @@ <h4 id="viewport-relative-lengths">
 		<p class=issue>Do we need this now that we have the min() function?
 	</dl>
 
+	<p class='note'>Note that Paged Media defines how the initial containing block
+	transforms across varying page widths.  This also affects these units.</p>
+
 <h3 id="absolute-lengths">
 Absolute lengths: the ''cm'', ''mm'', ''in'', ''pt'', ''pc'', ''px'' units</h3>