Update the user guide so it talks about the newer "do rec" notation everywhere

Some of the problems highlighted in trac #3968.

docs/users_guide/flags.xml

@@ -910,9 +910,15 @@
 	      <entry>dynamic</entry>
 	      <entry><option>-XNoTypeOperators</option></entry>
 	    </row>
+	    <row>
+	      <entry><option>-XDoRec</option></entry>
+	      <entry>Enable <link linkend="recursive-do-notation">recursive do notation</link>.</entry>
+	      <entry>dynamic</entry>
+	      <entry><option>-XNoDoRec</option></entry>
+	    </row>
 	    <row>
 	      <entry><option>-XRecursiveDo</option></entry>
-	      <entry>Enable <link linkend="mdo-notation">recursive do (mdo) notation</link>.</entry>
+	      <entry>Enable <link linkend="mdo-notation">recursive do (mdo) notation</link>. This is deprecated; please use <link linkend="recursive-do-notation">recursive do notation</link> instead.</entry>
 	      <entry>dynamic</entry>
 	      <entry><option>-XNoRecursiveDo</option></entry>
 	    </row>

docs/users_guide/glasgow_exts.xml

@@ -911,7 +911,7 @@ it, you can use the <option>-XNoNPlusKPatterns</option> flag.
 
     <!-- ===================== Recursive do-notation ===================  -->
 
-<sect2 id="mdo-notation">
+<sect2 id="recursive-do-notation">
 <title>The recursive do-notation
 </title>
 
@@ -1047,7 +1047,7 @@ It supports rebindable syntax (see <xref linkend="rebindable-syntax"/>).
 </para>
 </sect3>
 
-<sect3> <title> Mdo-notation (deprecated) </title>
+<sect3 id="mdo-notation"> <title> Mdo-notation (deprecated) </title>
 
 <para> GHC used to support the flag <option>-XRecursiveDo</option>,
 which enabled the keyword <literal>mdo</literal>, precisely as described in
@@ -1697,7 +1697,7 @@ and the fixity declaration applies wherever the binding is in scope.
 For example, in a <literal>let</literal>, it applies in the right-hand
 sides of other <literal>let</literal>-bindings and the body of the
 <literal>let</literal>C. Or, in recursive <literal>do</literal>
-expressions (<xref linkend="mdo-notation"/>), the local fixity
+expressions (<xref linkend="recursive-do-notation"/>), the local fixity
 declarations of a <literal>let</literal> statement scope over other
 statements in the group, just as the bound name does.
 </para>