resolver.5: Add an EXAMPLES section

In case local-unbound(8) fails for some reason, it could be useful
to have a basic resolv.conf(5) example in the manual page.

Reviewed by:	karels, pauamma
MFC after:	1 week
Differential Revision:	https://reviews.freebsd.org/D37183

share/man/man5/resolver.5

@@ -28,7 +28,7 @@
 .\"     @(#)resolver.5	8.1 (Berkeley) 6/5/93
 .\" $FreeBSD$
 .\"
-.Dd September 15, 2022
+.Dd November 7, 2022
 .Dt RESOLVER 5
 .Os
 .Sh NAME
@@ -220,6 +220,29 @@ The file
 resides in
 .Pa /etc .
 .El
+.Sh EXAMPLES
+A basic resolv.conf file could be in the following form.
+.Bd -literal -offset indent
+# The domain directive is only necessary, if your local
+# router advertises something like localdomain and you have
+# set up your hostnames via an external domain.
+domain localdomain.tld
+
+# In case you a running a local dns server or caching name server
+# like local-unbound(8) for example.
+nameserver 127.0.0.1
+
+# IP address of the local or ISP name service
+nameserver 192.168.2.1
+
+# Fallback nameservers, in this case these from Google.
+nameserver 8.8.8.8
+nameserver 4.4.4.4
+
+# Attach an OPT pseudo-RR for the EDNS0 extension,
+# as specified in RFC 2671.
+options edns0
+.Ed
 .Sh SEE ALSO
 .Xr gethostbyname 3 ,
 .Xr resolver 3 ,