Don't mention private classes in our docs.

Change-Id: I2cb7443ffa9afac8160b9510df95a304936a01c9
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

src/corelib/mimetypes/qmimetypeparser.cpp

@@ -85,7 +85,7 @@ static const char matchMaskAttributeC[] = "mask";
     \class QMimeTypeParser
     \inmodule QtCore
     \internal
-    \brief The QMimeTypeParser class parses MIME types, and builds a MIME database hierarchy by adding to QMimeDatabasePrivate.
+    \brief The QMimeTypeParser class parses MIME types, and builds a MIME database hierarchy by adding to QMimeDatabase.
 
     Populates QMimeDataBase