Move the submitting-changes down, after coding conventions

doc/manual.xml

···
 
   <xi:include href="introduction.xml" />
   <xi:include href="quick-start.xml" />
-  <xi:include href="submitting-changes.xml" />
   <xi:include href="stdenv.xml" />
   <xi:include href="packageconfig.xml" />
   <xi:include href="functions.xml" />
···
   <xi:include href="language-support.xml" />
   <xi:include href="package-notes.xml" />
   <xi:include href="coding-conventions.xml" />
+  <xi:include href="submitting-changes.xml" />
   <xi:include href="haskell-users-guide.xml" />
   <xi:include href="contributing.xml" />