Add dns command to configure DNS resolving in chronyc

chrony.texi

@@ -2544,6 +2544,8 @@ This option allows the user to specify the UDP port number which the
 target @code{chronyd} is using for its command & monitoring connections.
 This defaults to the compiled-in default; there would rarely be a need
 to change this.
+@item -n
+This option disables resolving IP addresses to hostnames.
 @item -4
 With this option hostnames will be resolved only to IPv4 addresses.
 @item -6
@@ -2584,6 +2586,7 @@ Only the following commands can be used @emph{without} providing a
 password:
 
 @itemize @bullet
+@item @code{dns}
 @item @code{exit}
 @item @code{help}
 @item @code{password}
@@ -2623,6 +2626,7 @@ interface.
 * delete command::              Remove an NTP server or peer
 * deny command ::               Denying NTP client access
 * deny all command::            Denying NTP client access
+* dns command::                 Configure how are hostnames and IP addresses resolved
 * dump command::                Dump measurement histories to files
 * exit command::                Exit from chronyc
 * help command::                Generate help summary
@@ -2983,6 +2987,32 @@ deny
 The effect of the allow command is identical to the @code{deny all}
 directive in the configuration file (@pxref{deny directive}).
 @c }}}
+@c {{{ dns
+@node dns command
+@subsubsection dns
+The @code{dns} command configures how are hostnames and IP addresses resolved in
+@code{chronyc}.  IP addresses can be resolved to hostnames when printing results
+of @code{sources}, @code{sourcestats}, @code{tracking} and @code{clients}
+commands.  Hostnames are resolved in commands that take an address as argument.
+
+There are five forms of the command:
+
+@table @code
+@item dns -n
+Disables resolving IP addresses to hostnames.  Raw IP addresses will be
+displayed.
+@item dns +n
+Enables resolving IP addresses to hostnames.  This is the default unless
+@code{chronyc} was started with @code{-n} option.
+@item dns -4
+Resolves hostnames only to IPv4 addresses.
+@item dns -6
+Resolves hostnames only to IPv6 addresses.
+@item dns -46
+Resolves hostnames to both address families.  This is the default unless
+@code{chronyc} was started with @code{-4} or @code{-6} option.
+@end table
+@c }}}
 @c {{{ dump
 @node dump command
 @subsubsection dump