Doc: Fix readString() and readByteArray() code snippets

Both of these functions return a StringResult, which has no
StringResult::code member. Instead, use the existing
StringResult::status member.

Fixes: QTBUG-122254
Pick-to: 6.7 6.6 6.5 6.2
Change-Id: I0b9bfa1fc9a30e9c542ab90f3d8f4243bdeda762
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>

src/corelib/doc/snippets/code/src_corelib_serialization_qcborstream.cpp

@@ -271,12 +271,12 @@ using namespace Qt::StringLiterals;
    {
        QString result;
        auto r = reader.readString();
-       while (r.code == QCborStreamReader::Ok) {
+       while (r.status == QCborStreamReader::Ok) {
            result += r.data;
            r = reader.readString();
        }
 
-       if (r.code == QCborStreamReader::Error) {
+       if (r.status == QCborStreamReader::Error) {
            // handle error condition
            result.clear();
        }
@@ -289,12 +289,12 @@ using namespace Qt::StringLiterals;
    {
        QBytearray result;
        auto r = reader.readBytearray();
-       while (r.code == QCborStreamReader::Ok) {
+       while (r.status == QCborStreamReader::Ok) {
            result += r.data;
            r = reader.readByteArray();
        }
 
-       if (r.code == QCborStreamReader::Error) {
+       if (r.status == QCborStreamReader::Error) {
            // handle error condition
            result.clear();
        }