Mark repo as not maintained

[Asone]

as i get through the same problem than the one intended to be fixed in #242 i got here.

Unfortunately i can see that this repo doesn't seem maintained anymore and yet, this tool seems to be quite used by dockerized ethereum bundles :/

Last merge was more than two years ago, and the related issue addressed quite the same amount of time.

@cubedro : Maybe updating the readme.md at least to inform that the repo is not maintained would be great so people know that if they want to implement it, issues might not be fixed. Also, if anyone knows an alternative or maintained version of the tool, adding it to the readme to provide the information to other users would be great.