Add a missing "\" to the markup.

Doc/lib/liblocale.tex

@@ -126,7 +126,7 @@ locale.setlocale(locale.LC_ALL, '')
   used.  \var{envvars} defaults to the search path used in GNU gettext;
   it must always contain the variable name \samp{LANG}.  The GNU
   gettext search path contains \code{'LANGUAGE'}, \code{'LC_ALL'},
-  code{'LC_CTYPE'}, and \code{'LANG'}, in that order.
+  \code{'LC_CTYPE'}, and \code{'LANG'}, in that order.
 
   Except for the code \code{'C'}, the language code corresponds to
   \rfc{1766}.  \var{language code} and \var{encoding} may be