[Improvement] We should have a full version list for documents

### What would you like to be improved?

Our project's documentation is version specific which is a general case for all open source projects.
For users who want to quickly access the specific version of document, there should be a place. Take Apache Spark for example: https://spark.apache.org/documentation.html, you can find historic versions of documents there. In our case (gravitino), the document link (https://gravitino.apache.org/docs/) will directly go to latest version.
I think we should have a full list there, given 0.6.1 is quickly out.

### How should we improve?

As I mentioned above, we should have a full version list of documents that can route to specific version.

Start at the documentation entry point, https://gravitino.apache.org/docs/, and compare its version navigation with the Apache Spark documentation page linked in the issue. Identify where the current latest-version routing is configured and define the version list and links so users can reach version 0.6.1 and other available document versions.

Written by the indexing model from the issue text.