Docs: tag newly added QFile and QFileInfo APIs as \since 5.15

Change-Id: I7d8605221a28cd05b4ebdbf20adf00ec3e121b58
Reviewed-by: Paul Wicking <paul.wicking@qt.io>

src/corelib/io/qfile.cpp

@@ -552,6 +552,8 @@ QFile::remove(const QString &fileName)
 }
 
 /*!
+    \since 5.15
+
     Moves the file specified by fileName() to the trash. Returns \c true if successful,
     and sets the fileName() to the path at which the file can be found within the trash;
     otherwise returns \c false.
@@ -586,6 +588,7 @@ QFile::moveToTrash()
 }
 
 /*!
+    \since 5.15
     \overload
 
     Moves the file specified by fileName() to the trash. Returns \c true if successful,

src/corelib/io/qfileinfo.cpp

@@ -1147,6 +1147,8 @@ bool QFileInfo::isShortcut() const
 
 
 /*!
+    \since 5.15
+
     Returns \c true if the object points to a junction;
     otherwise returns \c false.