[dcl.attr.nodiscard] Simplify note describing the string-literal in a

nodiscard attribute and make it less confusing.

Author: zygoloid

source/declarations.tex

@@ -9245,9 +9245,7 @@
 The \grammarterm{string-literal}
 in a \tcode{nodiscard} \grammarterm{attribute-argument-clause}
 is intended to be used in the message of the warning
-as the rationale for why the entity must not be discarded
-or to suggest alternative entities
-that may demonstrate the intent or proper usage.
+as the rationale for why the result should not be discarded.
 \end{note}
 
 \pnum