Add information to the readme 'ready' and 'exec' callback arguments
Add information to the readme
'ready' and 'exec' callback arguments

Signed-off-by: Mario Kozjak <33ca8347785e11ec875b554f3d6b1d87b5459732@gmail.com>

mwilliford/node-telnet-client,colinmathews/node-telnet-client,HaykoKoryun/node-telnet-client,loffelmacher/node-telnet-client,EyePulp/node-telnet-client,ChristopherHackett/node-telnet-client,canha/another-telnet-client,VPNht/node-telnet-client