Add note about .outerWidth() on border-collapse tables. Close gh-143.

entries/outerWidth.xml

@@ -11,7 +11,7 @@
   <longdesc>
     <p>Returns the width of the element, along with left and right padding, border, and optionally margin, in pixels.</p>
     <p>If <code>includeMargin</code> is omitted or <code>false</code>, the padding and border are included in the calculation; if <code>true</code>, the margin is also included.</p>
-    <p>This method is not applicable to <code>window</code> and <code>document</code> objects; for these, use <code><a href="/width">.width()</a></code> instead.</p>
+    <p>This method is not applicable to <code>window</code> and <code>document</code> objects; for these, use <code><a href="/width">.width()</a></code> instead. Although <code>.outerWidth()</code> can be used on table elements, it may give unexpected results on tables using the <code>border-collapse: collapse</code> CSS property.</p>
     <p class="image">
       <img src="/resources/0042_04_06.png"/>
     </p>