updated Readme

Author: pluto-tofu

README.md

@@ -3732,8 +3732,8 @@ 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/LeibnizFormulaForPi.cpp">
+  <img align="center" height="25" src="./logos/cplusplus.svg" />
   </a>
   </td>
   <td> <!-- Java -->