[css3-ruby] Add comment linking to EPUB's requirements doc for later analysis.

Author: fantasai

css3-ruby/Overview.html

@@ -662,6 +662,7 @@ <h3><a id="rubypos"></a>4.1 Ruby positioning: the <a href="#ruby-position">'ruby
       tone marks, when displaying. Tone marks are spacing characters that occur in memory at the end of the ruby text for each base character. They are usually displayed in a separate column to the right of the bopomofo characters, and the height of the tone mark depends on the number of characters in the syllable. One tone mark, however, is placed above the bopomofo, not to the right of it.</p>
       <p class="note"><span class="note-label">Note:</span> To make bopomofo annotations appear before or after the base text, like annotations for most other East Asian writing systems, use the 'before' and 'after' values of ruby-position.</p>
 	  <p>It is not defined how a user-agent should handle ruby text that is not bopomofo when the value of ruby-position is set to 'right'.</p>
+    <!-- See Taiwanese requirements doc for EPUB at http://epub-revision.googlecode.com/files/EGLS_TW_eng.ppt -->
     </dd>
 <dt><strong>inline</strong></dt>
 <dd>