[exec.counting.scopes.general] Fix typo (cplusplus#8193)

Author: Andreas-Krug

source/exec.tex

@@ -7819,7 +7819,7 @@
 
 \item
 \exposid{joined}:
-when the count of assocations drops to zero
+when the count of associations drops to zero
 while \tcode{scope} is in
 the \exposid{open-and-joining} or \exposid{closed-and-joining} state,
 \tcode{scope} moves to the \exposid{joined} state.