fix typo

Author: Vladimir Kotal

file-api.tex

@@ -237,7 +237,7 @@
 \item For both calls there are quite a few situations that can happen, and
 which are listed in the next few paragraphs.  If unsure, consult the standard.
 \item \texttt{read} returns a non-zero number of bytes less than \emph{nbyte} if
-less then \emph{nbyte} bytes remain in a file, if the call was interrupted
+less than \emph{nbyte} bytes remain in a file, if the call was interrupted
 by a signal, or if the file is a pipe, device, or socket and there is less than
 \emph{nbyte} bytes available at the moment.  If there is no data, a blocking
 \texttt{read} will block unless some data gets available, a non-blocking