Add an example of net_info usage.

bindings/ruby/examples/net_info.rb

@@ -0,0 +1,15 @@
+# Example illustrating the collecting of network information.
+
+require 'rbsigar'
+
+sigar = Sigar.new
+
+ninfo = sigar.net_info
+
+puts "Hostname:                  " + ninfo.host_name
+puts "Domain Name:               " + ninfo.domain_name
+puts "FQDN:                      " + sigar.fqdn
+puts "Default gateway:           " + ninfo.default_gateway
+puts "Default gateway interface: " + ninfo.default_gateway_interface
+puts "Primary DNS:               " + ninfo.primary_dns
+puts "Secondary DNS:             " + ninfo.secondary_dns