WebID definition -- proposal: drop the word 'uniquely'

"A WebID is an HTTP URI which uniquely denotes an Agent (Person,
Organization, Group, Device, etc.)."

I propose we drop 'uniquely'.  Unclear it adds anything here and may be
confusing (at least it was to me).

If the implication is that the webid contains 1 or more IFP that are
unique, it's not even clear to me how we would test that.