Extension without installation documentation

[luigiminardim]

Although it is understandable why this plug-in doesn't require to be placed in the Chrome's store, it would be useful to put in README how to install and execute this plug-in in the navigator.

[victoragcosta]

I totally forgot to upload my latest commit with a really basic (and maybe bad) instalation instructions. I'll keep this issue open though to remember me to make a better one