[website] Update docker version for 0.7.0 RC3 and 0.6.1

Author: wuchong

website/fluss-versions.json

@@ -9,13 +9,13 @@
     "versionName": "version-0.7",
     "fullVersion": "0.7.0",
     "shortVersion": "0.7",
-    "dockerVersion": "v0.7.0-rc2"
+    "dockerVersion": "v0.7.0-rc3"
   },
   {
     "versionName": "version-0.6",
     "fullVersion": "0.6.0",
     "shortVersion": "0.6",
-    "dockerVersion": "0.6.0"
+    "dockerVersion": "0.6.1"
   },
   {
     "versionName": "version-0.5",