qmp: fix typo in input-send-event examples

Lack of two closed bracket in json commands.
Signed-off-by: NAmos Kong <akong@redhat.com>
Reviewed-by: NMarkus Armbruster <armbru@redhat.com>
Signed-off-by: NMichael Tokarev <mjt@tls.msk.ru>

qmp-commands.hx

@@ -3820,13 +3820,13 @@ Press left mouse button.
 -> { "execute": "x-input-send-event",
     "arguments": { "console": 0,
                    "events": [ { "type": "btn",
-                    "data" : { "down": true, "button": "Left" } } } }
+                    "data" : { "down": true, "button": "Left" } } ] } }
 <- { "return": {} }
 
 -> { "execute": "x-input-send-event",
     "arguments": { "console": 0,
                    "events": [ { "type": "btn",
-                    "data" : { "down": false, "button": "Left" } } } }
+                    "data" : { "down": false, "button": "Left" } } ] } }
 <- { "return": {} }
 
 Example (2):