remove design notes vestiges

[snissn]

https://github.com/FIL-Builders/agent-hub/blob/main/blog/0004-first-steps-contributing-new-agent-agenthub.md

this blog references our design notes

somewhere in our documentation we must still reference the design notes

remove all vestigates of it

[snissn]

design notes make some sense maybe we want to move them into the yaml spec - it's still early so i don't mind having some inconsistency on design notes until we figure it out

when we have communitiy driven submissions it will be helpful to have notes on users intentions especially when you're choosing between multiple files, but when its just us generating agent files using the master spec it isn't helpful