Fix link for contributing

Author: rocky

index.html

@@ -256,11 +256,10 @@ <h2>Contributing</h2>
         <div class="inner align-left">
           <p>
             Please check out our contributing guide at
-            <a href="https://mathics-development-guide.readthedocs.io/en/latest/developing-code/contributing-developing.html">
-            mathics-development-guide.readthedocs.io/en/latest/developing-code/contributing-developing</a>.
-            <strong>Developers wanted! Please get in touch if you want
-            to be part of this awesome project.</strong>
+            <a href="https://mathics-development-guide.readthedocs.io/en/latest/extending/developing-code/contributing-developing.html">
+	      https://mathics-development-guide.readthedocs.io/en/latest/extending/developing-code/contributing-developing.html</a>.
           </p>
+          <p><strong>Developers wanted! Please get in touch if you want to be part of this awesome project.</strong></p>
         </div>
       </section>