Update wording for "C++ core language"

adoc/chapters/introduction.adoc

@@ -214,8 +214,8 @@ correct.
 
 A SYCL implementation must conform to {cpp17} or to one of the more recent {cpp}
 versions listed in <<sec:normativerefs>>.
-This version of {cpp} is subsequently referred to as the {cpp} core language in
-this document.
+The version of {cpp} to which a SYCL implementation conforms is referred to as
+the {cpp} core language in this document.
 All APIs in this specification are available regardless of the version of the
 {cpp} core language unless the description specifically states otherwise.
 If an API is documented with the phrase "Minimum C++ Version: __Version__", then