<programlisting> tags are rendered as blocks, and are not normally
used inside of a <para>. Previously, that was done here, which was
fine until I accidentally wrapped the paragraph which messes up the
formatting since <programlistings> are sensisitve to \n. This change
separates out the <programlisting> from the <para>, as is done
elsewhere in the handbook. Thanks to Tom Hukins for spotting my error
in accidentally wrapping the <programlisting>.