Doc: Update due to renaming QTextStream::readLine() overload

readLine() overload was renamed into readLineInto() in
21674735cc.

Change-Id: Iebd4c4e42ef4579c02ca38d7e41d00c3032130d8
Reviewed-by: Simon Hausmann <simon.hausmann@theqtcompany.com>

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

@@ -51,7 +51,7 @@ if (data.open(QFile::WriteOnly | QFile::Truncate)) {
 //! [1]
 QTextStream stream(stdin);
 QString line;
-while (stream.readLine(&line)) {
+while (stream.readLineInto(&line)) {
     ...
 }
 //! [1]

src/corelib/io/qtextstream.cpp

@@ -1612,7 +1612,7 @@ QString QTextStream::readLine(qint64 maxlen)
 
     If \a line has sufficient capacity for the data that is about to be
     read, this function may not need to allocate new memory. Because of
-    this, it can be faster than the other readLine() overload.
+    this, it can be faster than readLine().
 
     Returns \c false if the stream has read to the end of the file or
     an error has occurred; otherwise returns \c true. The contents in