Nagios plugin documentation fix (#2659)

docs/DATA_FORMATS_INPUT.md

@@ -428,13 +428,13 @@ Note: Nagios Input Data Formats is only supported in `exec` input plugin.
 ```toml
 [[inputs.exec]]
   ## Commands array
-  commands = ["/usr/lib/nagios/plugins/check_load", "-w 5,6,7 -c 7,8,9"]
+  commands = ["/usr/lib/nagios/plugins/check_load -w 5,6,7 -c 7,8,9"]
 
   ## measurement name suffix (for separating different commands)
   name_suffix = "_mycollector"
 
   ## Data format to consume.
-  ## Each data format has it's own unique set of configuration options, read
+  ## Each data format has its own unique set of configuration options, read
   ## more about them here:
   ## https://github.com/influxdata/telegraf/blob/master/docs/DATA_FORMATS_INPUT.md
   data_format = "nagios"