create more general concepts pages

content/2.general-concepts/0.index.md

content/2.general-concepts/3.defense-systems_trigger.md

content/2.general-concepts/4.defense-systems_effector.md

content/2.general-concepts/5.defense-systems-discovery.md

content/2.general-concepts/6.defensive-domains.md

content/2.general-concepts/7.MGE-defense-systems.md

content/2.general-concepts/8.anti-defense-systems..md