small fix to pointer syntax

Tutorials/T07-CppOverview/Slides/T7.tex

@@ -460,7 +460,7 @@ class Point {
       this->y = y;
     }
     double getX(){ return this->x; }
-    double getY(){ return this-y; }
+    double getY(){ return this->y; }
 };
 \end{lstlisting}
 \end{frame}