travelynx.conf: add influxdb documentation

examples/travelynx.conf

@@ -46,6 +46,14 @@
 		spare    => 2,
 	},
 
+	influxdb => {
+		# travelynx can log statistics and performance attributes to InfluxDB.
+		# To do so, create a travelynx database in your InfluxDB, and point url
+		# (below) to the corresponding write URL.  The URL may use anything from
+		# plain HTTP to HTTPS with password authentication.
+		## url => 'https://user:password@host/write?db=travelynx',
+	},
+
 	mail => {
 		# To disable outgoing mail for development purposes, uncomment the
 		# following line.  Mails will instead be logged as Mojolicious "info"