Include prettier on the template

[danielo515]

I'm not sure in which repository should open this kind of issues so I just open it on the main one, but you can point me to the correct one any time.

I noticed that rekit uses (or pretends to use) prettier as code formatter.
You should rather include it in the package.json of the template as a dependency o explain on the documentation that it is an opt-in feature and that it should be installed manually. Any option I think will work fine.

Regards