fix markup errors

Doc/lib/libfuncs.tex

@@ -884,9 +884,8 @@ class C(object):
   \samp{a[start:stop, i]}.
 \end{funcdesc}
 
-\begin{funcdesc}{sorted(\var{iterable}\optional{, \var{cmp}=None
-                                      \optional{, \var{key}=None
-                                      \optional{, \var{reverse}=False}}})}
+\begin{funcdesc}{sorted}{iterable\optional{, cmp\optional{,
+                         key\optional{, reverse}}}}
   Return a new sorted list from the items in \var{iterable}.
   The optional arguments \var{cmp}, \var{key}, and \var{reverse}
   have the same meaning as those for the \method{list.sort()} method.