[css-ruby-1] Update URL to EGLS doc

Author: fantasai

css-ruby-1/Overview.bs

@@ -1580,13 +1580,13 @@ Glossary</h2>
 			on the number of characters in the syllable.
 			The neutral tone mark, however,
 			is placed before (and in line with) the bopomofo, not alongside it.
+			<!-- See Taiwanese requirements doc for EPUB at https://lists.w3.org/Archives/Public/www-archive/2020Apr/att-0005/EGLS_TW_eng.ppt -->
 
 			Note: The user agent and font subsystem are responsible for
 			ensuring the correct relative alignment and positioning of glyphs,
 			including [=bopomofo tone marks=], when displaying text--
 			whether the text occurs in ruby annotations or as normal inline content.
 			Such glyph placement is not a function of CSS ruby layout.
-			<!-- See Taiwanese requirements doc for EPUB at http://epub-revision.googlecode.com/files/EGLS_TW_eng.ppt -->
 
 		<dt id="g-hanja">Hanja (Korean: <span lang=ko>漢字</span>)
 		<dd>