vnstati: add page (#6175)

pages/linux/vnstati.md

@@ -0,0 +1,20 @@
+# vnstati
+
+> PNG image output support for vnStat.
+> More information: <https://manned.org/vnstati>.
+
+- Output a summary of the last 2: months, days, and all-time:
+
+`vnstati --summary --iface {{network_interface}} --output {{path/to/output.png}}`
+
+- Output the 10 most traffic-intensive days of all time:
+
+`vnstati --top10 --iface {{network_interface}} --output {{path/to/output.png}}`
+
+- Output monthly traffic statistics from the last 12 months:
+
+`vnstati --months --iface {{network_interface}} --output {{path/to/output.png}}`
+
+- Output hourly traffic statistics from the last 24 hours:
+
+`vnstati --hours --iface {{network_interface}} --output {{path/to/output.png}}`