[cssom] Update an example

Author: Simon Pieters

cssom/Overview.html

@@ -1003,8 +1003,7 @@ <h4 id="the-cssstylesheet-interface"><span class="secno">6.1.2 </span>The <code
  <li><p>If the rule <var>newRule</var> cannot be inserted into the specified <var>index</var> due to constraints specified
  by <a href="#refsCSS">[CSS]</a>, then <a class="external" href="http://dom.spec.whatwg.org/#concept-throw" title="concept-throw">throw</a>
  a <code class="external"><a href="http://dom.spec.whatwg.org/#hierarchyrequesterror">HierarchyRequestError</a></code> exception.</p>
- <p class="note">For example, a CSS style sheet cannot contain more than one <code>@charset</code> rule, which,
- if present, must be the first rule.</li>
+ <p class="note">For example, a CSS style sheet cannot contain an <code title="">@import</code> at-rule after a rule set.</li>
  <li><p>Set <var>newRule</var><code>.parentStyleSheet</code> to <code>this</code> (i.e., this <code><a href="#cssstylesheet">CSSStyleSheet</a></code> instance object).</li>
  <li><p>Insert rule <var>newRule</var> into <code>cssRules</code> at the zero-indexed position <var>index</var>.<p></li>
  <li><p>Return <var>index</var>.</li>

cssom/Overview.src.html

@@ -933,8 +933,7 @@ <h4>The <code title>CSSStyleSheet</code> Interface</h4>
  <li><p>If the rule <var>newRule</var> cannot be inserted into the specified <var>index</var> due to constraints specified
  by <span data-anolis-ref>CSS</span>, then <span data-anolis-spec='dom' title='concept-throw'>throw</span>
  a <code data-anolis-spec='dom'>HierarchyRequestError</code> exception.</p>
- <p class='note'>For example, a CSS style sheet cannot contain more than one <code>@charset</code> rule, which,
- if present, must be the first rule.</p></li>
+ <p class='note'>For example, a CSS style sheet cannot contain an <code title>@import</code> at-rule after a rule set.</p></li>
  <li><p>Set <var>newRule</var><code>.parentStyleSheet</code> to <code>this</code> (i.e., this <code>CSSStyleSheet</code> instance object).</p></li>
  <li><p>Insert rule <var>newRule</var> into <code>cssRules</code> at the zero-indexed position <var>index</var>.<p></li>
  <li><p>Return <var>index</var>.</p></li>