Add a11y normalize in new docs

Author: JayPanoz

docs/CSS10c-custom_fonts.md

@@ -67,3 +67,9 @@ Then:
 document.documentElement.style.setProperty("--USER__fontWeight", "575");
 document.documentElement.style.setProperty("--USER__fontWidth", "125%");
 ```
+
+And for accessibility purposes, you can normalize text, which will remove all italics, font variants such as small capitals, subscript, and superscript formatting:
+
+```javascript
+document.documentElement.style.setProperty("--USER__a11yNormalize", "readium-a11y-on");
+```

docs/ReadiumCSS_docs.epub

@@ -78,6 +78,10 @@
 
       <pre><code>document.documentElement.style.setProperty("--USER__fontWeight", "575");
 document.documentElement.style.setProperty("--USER__fontWidth", "125%");</code></pre>
+
+      <p>And for accessibility purposes, you can normalize text, which will remove all italics, font variants such as small capitals, subscript, and superscript formatting:</p>
+
+      <pre><code>document.documentElement.style.setProperty("--USER__a11yNormalize", "readium-a11y-on");</code></pre>
     </section>
   </section>
 </body>