lok: MSForms: update callback's documentation.

Change-Id: I1bf41986f63a18abada7d268dc610df24b4c1144
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/94661
Tested-by: Jenkins
Reviewed-by: Tamás Zolnai <tamas.zolnai@collabora.com>
diff --git a/include/LibreOfficeKit/LibreOfficeKitEnums.h b/include/LibreOfficeKit/LibreOfficeKitEnums.h
index 32fd9f6..8a741d5 100644
--- a/include/LibreOfficeKit/LibreOfficeKitEnums.h
+++ b/include/LibreOfficeKit/LibreOfficeKitEnums.h
@@ -737,7 +737,12 @@ typedef enum
     * {
     *      "action": "show",
     *      "type": "drop-down",
     *      "textArea": "1418, 3906, 3111, 919"
     *      "textArea": "1418, 3906, 3111, 919",
     *      "params": {
     *           "items": ["January", "February", "July"],
     *           "selected": "2",
     *           "placeholder": "No items specified"
     *      }
     * }
     *
     * or