mention SFTP

Author: vladak

file-api.tex

@@ -1118,7 +1118,7 @@
 \item There is also a function \texttt{chroot} which changes the root
 directory of a calling process to a new one.  It is often used in various server
 implementations to limit access to the specific subtree.  For example, for an
-FTP server.  You have to be careful though and make sure it is not possible to
+(S)FTP server.  You have to be careful though and make sure it is not possible to
 escape from the chrooted subtree and access other parts of the filesystem.  The
 function is also not a part of SUSv4.
 \begin{itemize}