Change graphql api-docs path (#4771)

Signed-off-by: Suyeon Jung <[email protected]>

mkdocs/docs/experiments/api/contents.md

@@ -14,6 +14,6 @@
 <tr>
 <td>GraphQL Server</td>
 <td>Contains GraphQL Server API documentation</td>
-<td><a target="_" href="/litmus/graphql/v2.0.0/api.html">GraphQL Server</a></td>
+<td><a target="_" href="/litmus/graphql/v3.9.1/api.html">GraphQL Server</a></td>
 </tr>
 </table>