Merge pull request #22672 from kevinmeredith/correct_trapped_signals

Correct docs for a docker container's clean-up.

docs/reference/builder.md

@@ -834,7 +834,7 @@ does some more work:
 
 # USE the trap if you need to also do manual cleanup after the service is stopped,
 #     or need to start multiple services in the one container
-trap "echo TRAPed signal" HUP INT QUIT KILL TERM
+trap "echo TRAPed signal" HUP INT QUIT TERM
 
 # start service in background here
 /usr/sbin/apachectl start