Change the order of dependencies install

[louim]

Hey!

I noticed while following the readme, that the install order is wrong.

Installing eslint-plugin-prettier before prettier yield this error:

├── eslint-plugin-prettier@2.0.1
└── UNMET PEER DEPENDENCY prettier@>= 0.11.0

npm WARN eslint-plugin-prettier@2.0.1 requires a peer of prettier@>= 0.11.0 but none was installed.

So I swapped the steps in the readme. Cheers!

[not-an-aardvark]

Looks good to me. Thanks!