[dcl.link] Avoid implementation guidance in a note

Author: jensmaurer

source/declarations.tex

@@ -8129,12 +8129,12 @@
 Therefore, a linkage-specification with a \grammarterm{string-literal} that
 is unknown to the implementation requires a diagnostic.
 \end{note}
-\begin{note}
-It is recommended that the spelling of the \grammarterm{string-literal} be
+
+\recommended
+The spelling of the \grammarterm{string-literal} should be
 taken from the document defining that language. For example, \tcode{Ada}
 (not \tcode{ADA}) and \tcode{Fortran} or \tcode{FORTRAN}, depending on
 the vintage.
-\end{note}
 
 \pnum
 \indextext{specification!linkage!implementation-defined}%