Fix a few small markup/consistency nits.

Doc/lib/libshlex.tex

@@ -79,26 +79,28 @@ There is no corresponding `close' hook, but a shlex instance will call
 the \method{close()} method of the sourced input stream when it
 returns \EOF.
 
-For more explicit control of source stacking, use the next two
-methods. 
+For more explicit control of source stacking, use the
+\method{push_source()} and \method{pop_source()} methods. 
 \end{methoddesc}
 
 \begin{methoddesc}{push_source}{stream\optional{, filename}}
 Push an input source stream onto the input stack.  If the filename
 argument is specified it will later be available for use in error
 messages.  This is the same method used internally by the
-\method{sourcehook} method. (New in 2.1)
+\method{sourcehook} method.
+\versionadded{2.1}
 \end{methoddesc}
 
-\begin{methoddesc}{pop_source}{}}
+\begin{methoddesc}{pop_source}{}
 Pop the last-pushed input source from the input stack.
 This is the same method used internally when the lexer reaches
-\EOF on a stacked input stream. (New in 2.1)
+\EOF on a stacked input stream.
+\versionadded{2.1}
 \end{methoddesc}
 
 \begin{methoddesc}{error_leader}{\optional{file\optional{, line}}}
 This method generates an error message leader in the format of a
-\UNIX{} C compiler error label; the format is '"\%s", line \%d: ',
+\UNIX{} C compiler error label; the format is \code{'"\%s", line \%d: '},
 where the \samp{\%s} is replaced with the name of the current source
 file and the \samp{\%d} with the current input line number (the
 optional arguments can be used to override these).