[structure.requirements] Rephrase para 8 for clarity

Author: CaseyCarter

source/lib-intro.tex

@@ -505,8 +505,8 @@
 \pnum
 A declaration may explicitly impose requirements through its associated
 constraints\iref{temp.constr.decl}. When the associated constraints refer to a
-concept\iref{temp.concept}, additional semantic requirements are imposed on the
-use of the declaration.
+concept\iref{temp.concept}, the semantic constraints specified for that concept
+are additionally imposed on the use of the declaration.
 
 \rSec3[structure.specifications]{Detailed specifications}