Update Epub file

Author: JayPanoz

docs/CSS28-migration_guide.md

@@ -278,4 +278,6 @@ If you need to apply padding to the scroll view, you can use the `--RS__scrollPa
 
 ## Default line-length value has changed
 
-As of version `2.0.0` (stable), the default line-length when none is set by the user is `100%` instead of `40rem`. This is to prevent conflicts with the zoom factor.
+As of version `2.0.0` (stable), the default line-length when none is set by the user is `100%` instead of `40rem`. This is to prevent conflicts with the zoom factor.
+
+The custom property has been kept so that consumers of ReadiumCSS can still customize the value if they wish, especially as they can opt out of the new font-size implementation.

docs/ReadiumCSS_docs.epub

@@ -335,6 +335,8 @@ const backgroundColor = defaultColors.RS__backgroundColor;</code></pre>
       <h2 id="sigil_toc_id_225">Default line-length value has changed</h2>
 
       <p>As of version <code>2.0.0</code> (stable), the default line-length when none is set by the user is <code>100%</code> instead of <code>40rem</code>. This is to prevent conflicts with the zoom factor.</p>
+
+      <p>The custom property has been kept so that consumers of ReadiumCSS can still customize the value if they wish, especially as they can opt out of the new font-size implementation.</p>
     </section>
   </section>
 </body>