Update README for inputs.ping with correct cmd for native ping on Linux (#8787)
Update README for inputs.ping with correct cmd for native ping on Linux (#8787)

* Update readme  to enable native ping

* Provide more information on the numbers being set

* reference for ping_group_range already exists
li-ang/telegraf,oldmantaiter/telegraf,nferch/telegraf,nferch/telegraf,influxdata/telegraf,influxdata/telegraf,oldmantaiter/telegraf,Brightspace/telegraf,influxdata/telegraf,oldmantaiter/telegraf,Brightspace/telegraf,Brightspace/telegraf,li-ang/telegraf,li-ang/telegraf,nferch/telegraf