[exec.getcomplsigs] Add missing LaTeX escaping of braces (#7541)

Author: jensmaurer

source/exec.tex

@@ -2373,9 +2373,9 @@
 let \tcode{env} be an expression
 such that \tcode{decltype((env))} is \tcode{Env}.
 Let \tcode{new_sndr} be the expression
-\tcode{transform_sender(decltype(\exposid{get-domain-late}(sndr, env)){}, sndr, env)}, and
+\tcode{transform_sender(decltype(\exposid{get-domain-late}(sndr, env))\{\}, sndr, env)}, and
 let \tcode{NewSndr} be \tcode{decltype((new_sndr))}.
-Then \tcode{get_completion_signatures(sndr, env)} is expression-equivalent to
+Then \tcode{get_completion_signatures(sndr, env)} is expression-equiva\-lent to
 \tcode{(void(sndr), void(env), CS())}
 except that \tcode{void(sndr)} and \tcode{void(env)} are
 indeterminately sequenced,