Users regularly encounter difficulties when installing a package

[gremur]

Hello, according to multiple posts on stackoverflow.com users regularly encounter difficulties when installing python-nmap the package.

Main issues are:

1. Users installs nmap python library with pip install nmap instead of nmap binary. As far as nmap python library and python-nmap library share the same name of nmap module, the import nmap command raises AttributeError: module 'nmap' has no attribute 'PortScanner' error.
2. On the next step when users use pip uninstall nmap command in order to delete nmap python package they get next error Error: 'nmap program was not found in path. PATH

So misunderstanding with nmap installation is the main issue in installation process for python-nmap python package.
I have described how to solve the issue in stackoverflow post but i think it is not a best source for such data.

I believe the update of the README file with detail installation instruction and troubleshooting will help a lot of people.

Thank you.