fixup: remove space before \iref

Co-authored-by: Jan Schultke <[email protected]>

Author: dietmarkuehl

source/exec.tex

@@ -6395,7 +6395,7 @@
 
 \pnum
 \returns
-An awaitable object of unspecified type \iref{expr.await} whose
+An awaitable object of unspecified type\iref{expr.await} whose
 member functions arrange for the calling coroutine to be suspended
 and then completes the asynchronous operation associated with
 \tcode{STATE(*this)} by invoking \tcode{set_error(std::move(RCVR(*this)),