Update README.md

[gatorman22]

README Changes to simplify process of adding mods.

Description

Updates to section 'How to add mods' using latest official wiki/documentation. Included most of the original content as alternative steps (for some cases, this may be preferred).
Updates to section 'Define Host Registered Bind Address' to specify IPv4 support and offer resource for locating said address.

Checklist for all submissions

• Have you followed the guidelines in our Contributing document?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?
• Have you tested and reviewed your changes with confidence that everything works?
• Did you branch your changes and PR from that branch and not from your master branch?