Remove reference to error processing (that does not talk about invali…

…ding attributes) for invalid viewbox. Closes #52.

master/coords.html

@@ -277,11 +277,10 @@ <h2 id="ViewBoxAttribute">The <span class="attr-name">'viewBox'</span> attribute
 <a href="#ComputingAViewportsTransform">Computing the equivalent transform of an SVG viewport</a>.
 </p>
 
-<p>A negative value for <span
-class="attr-value">&lt;width&gt;</span> or <span
-class="attr-value">&lt;height&gt;</span> is an error (see <a
-href="implnote.html#ErrorProcessing">Error processing</a>). A
-value of zero disables rendering of the element.</p>
+<p>A negative value for <span class="attr-value">&lt;width&gt;</span> or
+<span class="attr-value">&lt;height&gt;</span> is an error and invalidates
+the <a>'viewBox'</a> attribute. A value of zero disables rendering of the
+element.</p>
 
 <div class="example">
 <p id="ExampleViewBox"><span class="example-ref">Example ViewBox</span> illustrates