doc: document long options

Document the --version and --help options in chronyd and chronyc man
page.

client.c

@@ -3506,7 +3506,7 @@ main(int argc, char **argv)
   int opt, ret = 1, multi = 0, family = IPADDR_UNSPEC;
   int port = DEFAULT_CANDM_PORT;
 
-  /* Parse (undocumented) long command-line options */
+  /* Parse long command-line options */
   for (optind = 1; optind < argc; optind++) {
     if (!strcmp("--help", argv[optind])) {
       print_help(progname);

doc/chronyc.adoc

@@ -118,10 +118,14 @@ This option is ignored and is provided only for compatibility.
 *-a*::
 This option is ignored and is provided only for compatibility.
 
-*-v*::
+*-v*, *--version*::
 With this option *chronyc* displays its version number on the terminal and
 exits.
 
+*--help*::
+With this option *chronyc* displays a help message on the terminal and
+exits.
+
 == COMMANDS
 
 This section describes each of the commands available within the *chronyc*

doc/chronyd.adoc

@@ -187,9 +187,12 @@ still track its offset and frequency relative to the estimated true time. This
 option allows *chronyd* to be started without the capability to adjust or set
 the system clock (e.g. in some containers) to operate as an NTP server.
 
-*-v*::
+*-v*, *--version*::
 With this option *chronyd* will print version number to the terminal and exit.
 
+*-h*, *--help*::
+With this option *chronyd* will print a help message to the terminal and exit.
+
 == FILES
 
 _@SYSCONFDIR@/chrony.conf_

main.c

@@ -417,7 +417,7 @@ int main
 
   LOG_Initialise();
 
-  /* Parse (undocumented) long command-line options */
+  /* Parse long command-line options */
   for (optind = 1; optind < argc; optind++) {
     if (!strcmp("--help", argv[optind])) {
       print_help(progname);