Fix link to page layout. Change vertical_text to writing_mode.

Author: r12a

index.html

@@ -72,7 +72,7 @@ <h1>Type samples</h1>
 <option value="">All topics</option>
 
 <optgroup label="Text direction">
-<option value="vertical_text">Vertical text</option>
+<option value="writing_mode">Vertical text</option>
 <option value="bidi_text">Bidirectional text</option>
 </optgroup>
 
@@ -109,7 +109,7 @@ <h1>Type samples</h1>
 </optgroup>
 
 <optgroup label="Page & book layout">
-<option value="line_breaking">General page layout &amp; progression</option>
+<option value="page_layout">General page layout &amp; progression</option>
 <option value="grids_tables">Grids &amp; tables</option>
 <option value="footnotes_etc">Footnotes, endnotes, etc.</option>
 <option value="headers_footers">Page headers, footers, etc.</option>