[FLINK-28396][doc] Updating config file with previous doc version

diff --git a/docs/config.toml b/docs/config.toml
index f3bce0b..bf02cd8 100644
--- a/docs/config.toml
+++ b/docs/config.toml
@@ -61,6 +61,7 @@
   ]
 
   PreviousDocs = [
+    ["0.1", "https://nightlies.apache.org/flink/flink-kubernetes-operator-docs-release-0.1"]
   ]
 
 [markup]