[exec.as.awaitable] Improve formatting of new concept

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

Author: AlisdairM

source/exec.tex

@@ -5461,9 +5461,9 @@
       };
 
   template<class Sndr>
-    concept @\defexposconcept{has-queryable-await-completion-adaptor}@              // \expos
-      = @\libconcept{sender}@<Sndr>
-        && requires(Sndr&& sender) {
+    concept @\defexposconcept{has-queryable-await-completion-adaptor}@ =            // \expos
+      @\libconcept{sender}@<Sndr> &&
+      requires(Sndr&& sender) {
         get_await_completion_adaptor(get_env(sender));
       };