add missing caching command in client help (#7399)

(cherry picked from commit e035e5218f4245f5fa5eb0cafc56c572d9f4fa15)

src/networking.c

@@ -2147,6 +2147,7 @@ void clientCommand(client *c) {
 "SETNAME <name>         -- Assign the name <name> to the current connection.",
 "UNBLOCK <clientid> [TIMEOUT|ERROR] -- Unblock the specified blocked client.",
 "TRACKING (on|off) [REDIRECT <id>] [BCAST] [PREFIX first] [PREFIX second] [OPTIN] [OPTOUT]... -- Enable client keys tracking for client side caching.",
+"CACHING  (yes|no)      -- Enable/Disable tracking of the keys for next command in OPTIN/OPTOUT mode.",
 "GETREDIR               -- Return the client ID we are redirecting to when tracking is enabled.",
 NULL
         };