Add item to Frequently Asked Questions of Tramp manual

* doc/misc/tramp.texi (Frequently Asked Questions): Add item for
ControlMaster option on proxy hosts.  Explain changing syntax to
Ange FTP.

doc/misc/tramp.texi

@@ -4082,6 +4082,31 @@ this @code{nil} setting:
 @end lisp
 
 
+@item
+On multi-hop connections, @value{tramp} does not use @command{ssh}
+@code{ControlMaster}
+
+In order to use the @code{ControlMaster} option, @value{tramp} must
+check whether the @command{ssh} client supports this option.  This is
+only possible on the local host, for the first hop.  @value{tramp}
+does not use this option on proxy hosts.
+
+If you want to use this option also for the other hops, you must
+configure @file{~/.ssh/config} on the proxy host:
+
+@example
+@group
+Host *
+     ControlMaster	auto
+     ControlPath	tramp.%C
+     ControlPersist	no
+@end group
+@end example
+
+Check @command{man ssh_config} whether these options are supported on
+your proxy host.
+
+
 @item
 File name completion does not work with @value{tramp}
 
@@ -4606,6 +4631,12 @@ in @file{.emacs}:
 (customize-set-variable 'tramp-default-method "ftp")
 @end lisp
 
+If you want to enable Ange FTP's syntax, add the following form:
+
+@lisp
+(tramp-change-syntax 'simplified)
+@end lisp
+
 @item
 @vindex tramp-mode
 To disable both @value{tramp} (and Ange FTP), set @code{tramp-mode} to