Fix missing Python 0.4.0 doc link
diff --git a/themes/docsy/layouts/docs/baseof.html b/themes/docsy/layouts/docs/baseof.html
index d38d8a7..3284120 100644
--- a/themes/docsy/layouts/docs/baseof.html
+++ b/themes/docsy/layouts/docs/baseof.html
@@ -113,7 +113,7 @@
                           docs
                         </button>
                         <div class="dropdown-menu">
-                          <a class="dropdown-item" target="_blank" href="https://github.com/apache/skywalking-python/tree/v0.3.0">v0.3.0</a>
+                          <a class="dropdown-item" target="_blank" href="https://github.com/apache/skywalking-python/tree/v0.4.0">v0.4.0</a>
                         </div>
                       </div>