[skip ci] Fix FRR105 with feedback for #675

Address some feedback about wording and style  of the unique ID req.

src/validations/constraints/STYLE.md

@@ -384,7 +384,7 @@ State: Required
 
 Categories: ID; Metadata
 
-Guidance: Developers MUST define a Metaschema constraint with an `id` flag that is unique to all the constraints that FedRAMP maintains across all constraint documents.
+Guidance: Developers MUST define a Metaschema constraint with an `id` flag, and the value of that `id` flag must be unique from all other constraint IDs across all constraint documents FedRAMP and NIST define in core OSCAL.
 
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