Add documentation for alias files

[Rigo-m]

Add small example on how an alias config file should be made

[mesqueeb]

@boydaihungst could you provide a short example in the readme on this?

[boydaihungst]

Sure. @Rigo-m Check this gist.
https://gist.github.com/boydaihungst/5a273fed3fb6d01a808aacd2f4b76bdc