fix: Fixed typo in upgrade guide (#1321)
fix: Fixed typo in upgrade guide (#1321)

see also http://www.dictionary.com/browse/per-say
EmergingTechnologyAdvisors/node-serialport,node-serialport/node-serialport,voodootikigod/node-serialport,voodootikigod/node-serialport,EmergingTechnologyAdvisors/node-serialport,voodootikigod/node-serialport,EmergingTechnologyAdvisors/node-serialport,voodootikigod/node-serialport,node-serialport/node-serialport,node-serialport/node-serialport,node-serialport/node-serialport,EmergingTechnologyAdvisors/node-serialport,EmergingTechnologyAdvisors/node-serialport,node-serialport/node-serialport