[expr.await] Clarify rethrowing exceptions from await-suspend

Author: jensmaurer

source/expressions.tex

@@ -4597,7 +4597,8 @@
 
 \item
 If the result of \placeholder{await-ready} is \tcode{true},
-or when the coroutine is resumed,
+or when the coroutine is resumed
+other than by rethrowing an exception from \placeholder{await-suspend},
 the \placeholder{await-resume} expression is evaluated, and
 its result is the result of the \grammarterm{await-expression}.
 \end{itemize}