Fix spelling.

Doc/lib/libxdrlib.tex

@@ -33,7 +33,7 @@ values from a string buffer.  The input buffer is given as
   \seerfc{1014}{XDR: External Data Representation Standard}{This RFC
                 defined the encoding of data which was XDR at the time
                 this module was originally written.  It has
-                appearantly been obsoleted by \rfc{1832}.}
+                apparently been obsoleted by \rfc{1832}.}
 
   \seerfc{1832}{XDR: External Data Representation Standard}{Newer RFC
                 that provides a revised definition of XDR.}