Minor readme issues

[lassehe]

Here is some questions or notes about the README.md file:

• In requirements is line "VM host with TWO network interfaces". Why is this? I'm pretty sure booterizer worked out-of-the-box for me on a computer with a single NIC. Or does "VM host" here refer to the Vagrant VM? In either case I'm missing the point of this requirement/recommendation.
• It remains bit foggy if this version supports IRIX 5.3 or not. It is mentioned, with a slightly confusing link to "Callahan's Booterizer", but not mentioned elsewhere. Notably not in the target table or OS list.
• Inconsistent use of both spellings 'booterizer' and 'Booterizer' leaves it unclear which should be followed.
• irix_ansible guide here seems bit incomplete and possibly confusing. Would it be better just to provide a very brief description and a link to corresponding repository readme, to avoid redundancy?