Hi Johnny,
Good that you reached out. Indeed we are in the process of moving documentation to the new website, so the links have changed. Old website is available at wiki.flashrom.org address.
In your case, for overall dev guides, new link is: https://www.flashrom.org/dev_guide/development_guide.html Instructions how to add new chip hasn't been migrated yet, you can access them by the link: https://wiki.flashrom.org/Development_Guidelines#Adding/reviewing_a_new_flas...
Feel free to reach out if you have any more questions along the way.