[coro.generator.members] Add missing \exposid

Author: lprv

source/ranges.tex

@@ -17222,7 +17222,7 @@
 Initializes \exposid{coroutine_} with
 \tcode{exchange(other.\exposid{coroutine_}, \{\})} and
 \exposid{active_} with
-\tcode{exchange(\brk{}other.active_, nullptr)}.
+\tcode{exchange(\brk{}other.\exposid{active_}, nullptr)}.
 
 \pnum
 \begin{note}