ntp: Improve descriptions in man pages

+ ntpd added to ntp.conf(5) description (search keywords)
+ expand NTP so these pages are shown when `apropos time`
+ "standard" => "reference" for increased consistency
- removed redundant or duplicated search keywords

ntp.org bug:	https://bugs.ntp.org/show_bug.cgi?id=3936
MFC after:	3 days
Reviewed by:	Harlan Stenn <stenn@nwtime.org>
Reviewed by:	Cy Schubert <cy@nwtime.org>

contrib/ntp/ntpd/ntp.conf.def

@@ -9,7 +9,7 @@ autogen definitions options;
 // file name.
 prog-name	= "ntp.conf";
 file-path	= "/etc/ntp.conf";
-prog-title	= "Network Time Protocol (NTP) daemon configuration file format";
+prog-title	= "Network Time Protocol daemon (ntpd) configuration format";
 
 /* explain: Additional information whenever the usage routine is invoked */
 explain = <<- _END_EXPLAIN

contrib/ntp/ntpd/ntp.keys.def

@@ -10,7 +10,7 @@ autogen definitions options;
 // file name.
 prog-name	= "ntp.keys";
 file-path	= "/etc/ntp.keys";
-prog-title	= "NTP symmetric key file format";
+prog-title	= "Network Time Protocol symmetric key format";
 
 /* explain: Additional information whenever the usage routine is invoked */
 explain = <<- _END_EXPLAIN

contrib/ntp/ntpd/ntpd-opts.def

@@ -5,7 +5,7 @@ autogen definitions options;
 #include copyright.def
 
 prog-name	= "ntpd";
-prog-title	= "NTP daemon program";
+prog-title	= "set clock via Network Time Protocol daemon";
 argument	= "[ <server1> ... <serverN> ]";
 
 #include ntpdbase-opts.def

contrib/ntp/ntpq/ntpq-opts.def

@@ -7,7 +7,7 @@ autogen definitions options;
 #include autogen-version.def
 
 prog-name      = "ntpq";
-prog-title     = "standard NTP query program";
+prog-title     = "query Network Time Protocol servers";
 argument       = '[ host ...]';
 
 flag = {

contrib/ntp/sntp/sntp-opts.def

@@ -6,7 +6,7 @@ autogen definitions options;
 #include copyright.def
 
 prog-name      = "sntp";
-prog-title	= "standard Simple Network Time Protocol client program";
+prog-title	= "reference Simple Network Time Protocol client";
 argument	= '[ hostname-or-IP ...]';
 
 #include homerc.def

contrib/ntp/util/ntp-keygen-opts.def

@@ -7,7 +7,7 @@ autogen definitions options;
 #include autogen-version.def
 
 prog-name      = "ntp-keygen";
-prog-title     = "Create a NTP host key";
+prog-title     = "create a Network Time Protocol host key";
 package        = ntp;
 
 include        = '#include <stdlib.h>';

usr.sbin/ntp/doc/ntp-keygen.8

@@ -8,7 +8,7 @@
 .\"  and the template file   agmdoc-cmd.tpl
 .Sh NAME
 .Nm ntp-keygen
-.Nd Create a NTP host key
+.Nd create a Network Time Protocol host key
 .Sh SYNOPSIS
 .Nm
 .\" Mixture of short (flag) options and long options

usr.sbin/ntp/doc/ntp.conf.5

@@ -8,7 +8,7 @@
 .\"  and the template file   agmdoc-cmd.tpl
 .Sh NAME
 .Nm ntp.conf
-.Nd Network Time Protocol (NTP) daemon configuration file format
+.Nd Network Time Protocol daemon (ntpd) configuration format
 .Sh SYNOPSIS
 .Nm
 .Op Fl \-option\-name

usr.sbin/ntp/doc/ntp.keys.5

@@ -12,7 +12,7 @@
 
 .Sh NAME
 .Nm ntp.keys
-.Nd NTP symmetric key file format
+.Nd Network Time Protocol symmetric key format
 .Sh SYNOPSIS
 .Nm
 .Op Fl \-option\-name

usr.sbin/ntp/doc/ntpd.8

@@ -8,7 +8,7 @@
 .\"  and the template file   agmdoc-cmd.tpl
 .Sh NAME
 .Nm ntpd
-.Nd NTP daemon program
+.Nd set clock via Network Time Protocol daemon
 .Sh SYNOPSIS
 .Nm
 .\" Mixture of short (flag) options and long options

usr.sbin/ntp/doc/ntpq.8

@@ -8,7 +8,7 @@
 .\"  and the template file   agmdoc-cmd.tpl
 .Sh NAME
 .Nm ntpq
-.Nd standard NTP query program
+.Nd query Network Time Protocol servers
 .Sh SYNOPSIS
 .Nm
 .\" Mixture of short (flag) options and long options

usr.sbin/ntp/doc/sntp.8

@@ -8,7 +8,7 @@
 .\"  and the template file   agmdoc-cmd.tpl
 .Sh NAME
 .Nm sntp
-.Nd standard Simple Network Time Protocol client program
+.Nd reference Simple Network Time Protocol client
 .Sh SYNOPSIS
 .Nm
 .\" Mixture of short (flag) options and long options