DOCS - Document scope and purpose

I think it would be beneficial for users if there was some clear guidance around the problems / issues the installer is attempting to solve. At least we should make clear that it does not ship with any versions of python, instead it installs python from the usual web sources and therefore requires unrestricted access to the relevant websites to make the install.

This means that if a user is in an environment where IT policy prevents installation of python or access to pypi.org and friends this tool will not help. It is intended only as a tool to assist in python installation if it is already possible to do so.