https://submarine.apache.org/ should not show the master branch documentation?

[xunliu]

I see that https://submarine.apache.org/ is showing the documentation of the previous version (0.6),
the slack information in the 0.6 documentation is wrong（https://submarine.apache.org/docs/community/README/）,
and the master branch doc is correct（https://submarine.apache.org/docs/next/community/README/#communicating）.

So, should I show the master branch documentation?

[pingsutw]

I think we should update 0.6.0 docs. we should show stable documentation for users.