pip properly not indicated in readme.md

[prdp1137]

pip is documented in the readme, but as the tool is based in python3 pip3 is needed to install the requirements.

[anuraghazra]

@all-contributors please add @pr0d33p for doc, bug

[allcontributors]

@anuraghazra

I've put up a pull request to add @pr0d33p! 🎉