uri: Reorder classes (#5469)

This reorders the classes within the URI documentation to list the two URI
implementations first, then the UriComparisonMode enum and lastly the
Exceptions and Exception-related classes.

Author: TimWolla

reference/uri/book.xml

@@ -21,15 +21,16 @@
   </simpara>
  </preface>
 
- &reference.uri.uri.invaliduriexception;
- &reference.uri.uri.uricomparisonmode;
- &reference.uri.uri.urierror;
- &reference.uri.uri.uriexception;
-
  &reference.uri.uri.rfc3986.uri;
 
- &reference.uri.uri.whatwg.invalidurlexception;
  &reference.uri.uri.whatwg.url;
+
+ &reference.uri.uri.uricomparisonmode;
+
+ &reference.uri.uri.uriexception;
+ &reference.uri.uri.urierror;
+ &reference.uri.uri.invaliduriexception;
+ &reference.uri.uri.whatwg.invalidurlexception;
  &reference.uri.uri.whatwg.urlvalidationerror;
  &reference.uri.uri.whatwg.urlvalidationerrortype;
 </book>