[docs] Update latest version of v0.6 to 0.6.1

Author: wuchong

website/fluss-versions.json

@@ -13,7 +13,7 @@
   },
   {
     "versionName": "version-0.6",
-    "fullVersion": "0.6.0",
+    "fullVersion": "0.6.1",
     "shortVersion": "0.6",
     "dockerVersion": "0.6.1"
   },