inetd(8): Add comments to all examples

Submitted by:	debdrup (with some minor changes by kevans)
Reviewed by:	bcr (manpages)
MFC after:	3 days
Differential Revision:	https://reviews.freebsd.org/D24818

usr.sbin/inetd/inetd.8

@@ -28,7 +28,7 @@
 .\"     from: @(#)inetd.8	8.3 (Berkeley) 4/13/94
 .\" $FreeBSD$
 .\"
-.Dd May 12, 2020
+.Dd May 14, 2020
 .Dt INETD 8
 .Os
 .Sh NAME
@@ -793,16 +793,30 @@ the pid of the currently running
 .Sh "EXAMPLES"
 Here are several example service entries for the various types of services:
 .Bd -literal
+# The first four launch the relevant daemon when a connection on a port
+# as defined by /etc/services is opened.
 ftp          stream  tcp   nowait root  /usr/libexec/ftpd        ftpd -l
 ntalk        dgram   udp   wait   root  /usr/libexec/ntalkd      ntalkd
 telnet       stream  tcp6  nowait root  /usr/libexec/telnetd  telnetd
 shell        stream  tcp46  nowait root  /usr/libexec/rshd rshd
+
+# Let the system respond to date requests via tcpmux
 tcpmux/+date stream  tcp   nowait guest /bin/date                date
+
+# Let people access the system phonebook via tcpmux
 tcpmux/phonebook stream tcp nowait guest /usr/local/bin/phonebook phonebook
+
+# Make kernel statistics accessible
 rstatd/1-3   dgram   rpc/udp wait root  /usr/libexec/rpc.rstatd  rpc.rstatd
+
 # Use netcat as a one-shot HTTP proxy with nc (from freebsd-tips fortune)
 http         stream  tcp   nowait nobody /usr/bin/nc nc -N dest-ip 80
-/var/run/echo stream unix  nowait root	internal
+
+# Set up a unix socket at /var/run/echo that echo's back whatever is written
+# to it.
+/var/run/echo stream unix  nowait root  internal
+
+# Run chargen for IPsec Authentication Headers
 #@ ipsec ah/require
 chargen      stream  tcp   nowait root  internal
 #@