Only show the section on radio tags if the target has a radio.

git-svn-id: svn://svn.rockbox.org/rockbox/branches/v3_6@26392 a1c6a512-1295-4272-9138-f99709370657

manual/appendix/wps_tags.tex

@@ -378,6 +378,7 @@ Examples:
 \end{enumerate}
 }
 
+\opt{radio}{
 \section{FM Radio}
   \begin{tagmap}
     \config{\%tp} & Does this target have a radio? If it doesn't, the ``true''
@@ -406,6 +407,7 @@ described above. Images need to be placed in \fname{/.rockbox/fmpresets/},
 and must have the same name as the preset. They need to be in either
 \fname{.bmp} or \fname{.jpg} format, and the radio must be in preset mode
 and tuned to a preset (and not recording) in order for them to be shown.
+}
 
 \section{Alignment}
   \begin{tagmap}