Set default docs version to 0.25.0 instead of master

Now, when a user visits https://docs.bazel.build, they will get redirected to https://docs.bazel.build/versions/0.25.0/bazel-overview.html.

Staging: https://bazel-docs-staging.netlify.com

Closes #8325.

Change-Id: I08dfa978ad543ede9cc2f04b8f66a5c0cb4e6b79
PiperOrigin-RevId: 248318528
diff --git a/site/docs/index.md b/site/docs/index.md
index b32fa5c..3fe07de 100644
--- a/site/docs/index.md
+++ b/site/docs/index.md
@@ -1,4 +1,10 @@
 ---
-layout: redirect
-redirect: bazel-overview.html
 ---
+
+<html>
+  <head>
+    <script>
+      window.location.replace("/versions/{{ site.version }}/bazel-overview.html");
+    </script>
+  </head>
+</html>
\ No newline at end of file