Make "etc" directory path more generic in docs

[shadyabhi]

Hi radoondas,

This is something pretty minor. I was just following the instructions and noticed this. It should use $GOPATHvariable instead of hard coded folder path.

What do you think?

Thanks

[radoondas]

@shadyabhi First of all thanks for your contribution! You are right, this is more generic. I'm glad that someone is trying it :)

[shadyabhi]

Thanks for the merge!