That's a bit misleading. agilemanifesto.org also hosts a (still short, but way more concrete) Twelve Principles of Agile Software: https://agilemanifesto.org/principles.html

(Also worth noting that scrum and most of the best known agile methodologies predate the manifesto; the manifesto was formed from guiding principles of those methodologies, not the other way around: https://agilemanifesto.org/history.html)