Doc: updated QString::fromRawData documentation to QRegularExpression

QString::fromRawData code sample still shows the use of QRegExp. This
patch updates it for QRegularExpression and cleans the code.

Change-Id: Iff0f736cdbdd7d35c65fde1496ce9f838a8f5c6d
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/corelib/doc/snippets/qstring/main.cpp

@@ -380,14 +380,14 @@ void Widget::fillFunction()
 void Widget::fromRawDataFunction()
 {
     //! [22]
-    QRegExp pattern;
+    QRegularExpression pattern("\u00A4");
     static const QChar unicode[] = {
             0x005A, 0x007F, 0x00A4, 0x0060,
             0x1009, 0x0020, 0x0020};
     int size = sizeof(unicode) / sizeof(QChar);
 
     QString str = QString::fromRawData(unicode, size);
-    if (str.contains(QRegExp(pattern))) {
+    if (str.contains(pattern) {
         // ...
     //! [22] //! [23]
     }

src/corelib/tools/qstring.cpp

@@ -8144,7 +8144,7 @@ bool QString::isRightToLeft() const
     to create a deep copy of the data, ensuring that the raw data
     isn't modified.
 
-    Here's an example of how we can use a QRegExp on raw data in
+    Here's an example of how we can use a QRegularExpression on raw data in
     memory without requiring to copy the data into a QString:
 
     \snippet qstring/main.cpp 22