Fix typpo.

Doc/lib/libfileinput.tex

@@ -169,7 +169,7 @@ The two following opening hooks are provided by this module:
   Transparently opens files compressed with gzip and bzip2 (recognized
   by the extensions \code{'.gz'} and \code{'.bz2'}) using the \module{gzip}
   and \module{bz2} modules.  If the filename extension is not \code{'.gz'}
-  or \code{'.bz2'}, the file is openned normally (ie,
+  or \code{'.bz2'}, the file is opened normally (ie,
   using \function{open()} without any decompression).
 
   Usage example: