Fix typo in valkey.conf file's shutdown section (valkey-io#1224)

Found typo "exists" ==> "exits" in valkey.conf in shutdown section.

Signed-off-by: Shivshankar-Reddy <[email protected]>

valkey.conf

@@ -1580,7 +1580,7 @@ aof-timestamp-enabled no
 # Maximum time to wait for replicas when shutting down, in seconds.
 #
 # During shut down, a grace period allows any lagging replicas to catch up with
-# the latest replication offset before the primary exists. This period can
+# the latest replication offset before the primary exits. This period can
 # prevent data loss, especially for deployments without configured disk backups.
 #
 # The 'shutdown-timeout' value is the grace period's duration in seconds. It is