Update README.md

Author: kelvins

README.md

@@ -1698,8 +1698,8 @@ In order to achieve greater coverage and encourage more people to contribute to
                 </a>
             </td>
             <td> <!-- C++ -->
-                <a href="./CONTRIBUTING.md">
-                    <img align="center" height="25" src="./logos/github.svg" />
+                <a href="./src/cpp/BinaryTree.cpp">
+                    <img align="center" height="25" src="./logos/cplusplus.svg" />
                 </a>
             </td>
             <td> <!-- Java -->