Removing the word "uniquely" from the "DESCRIPTION" of "Property Name" about oscal

[wendellpiez]

We discussed this in Gitter chat. The word 'uniquely' implies a constraint over the values of assigned names to props (prop objects), which is not actually applicable in most cases.

It is possible for applications and externally defined constraint sets to assert such rules when they are applicable, but that needs to be described elsewhere, not in the definition of prop/@name.

The offending sentence is this one:

a textual label, within a namespace, that uniquely identifies a specific attribute, characteristic, or quality of the property's containing object.

The word 'uniquely' can be struck from that sentence with no loss of meaning.