Add unbound input plugin (#3434)

etc/telegraf.conf

@@ -2887,6 +2887,19 @@
 #   # socket_listener plugin
 #   # see https://github.com/influxdata/telegraf/tree/master/plugins/inputs/socket_listener
 
+# # A plugin to collect stats from Unbound - a validating, recursive, and caching DNS resolver
+# [[inputs.unbound]]
+#   ## If running as a restricted user you can prepend sudo for additional access:
+#   #use_sudo = false
+#
+#   ## The default location of the unbound-control binary can be overridden with:
+#   binary = "/usr/sbin/unbound-control"
+#
+#   # The default timeout of 1s can be overriden with:
+#   #timeout = "1s"
+#
+#   # Use the builtin fielddrop/fieldpass telegraf filters in order to keep/remove specific fields
+#   fieldpass = ["total_*", "num_*","time_up", "mem_*"]
 
 # # A Webhooks Event collector
 # [[inputs.webhooks]]