Added comment as minggo requested

cocos2dx/label_nodes/CCLabelBMFont.cpp

@@ -1260,6 +1260,7 @@ void CCLabelBMFont::updateLabel()
             {
                 float lineWidth = 0.0f;
                 unsigned int line_length = last_line.size();
+				// if last line is empty we must just increase lineNumber and work with next line
                 if (line_length == 0)
                 {
                     lineNumber++;