Fixed typo in explanation of abspath(); noticed by Paul Prescod

<paul@prescod.net>.

Doc/lib/libposixpath.tex

@@ -11,7 +11,7 @@ This module implements some useful functions on pathnames.
 \begin{funcdesc}{abspath}{path}
 Return a normalized absolutized version of the pathname \var{path}.
 On most platforms, this is equivalent to
-\code{normpath(join(os.getcwd()), \var{path})}.
+\code{normpath(join(os.getcwd(), \var{path}))}.
 \versionadded{1.5.2}
 \end{funcdesc}