[Enhancement] Keep old version documents as they were

1. ~~The `Installation and deployment` and `SDK` category should be in front of the `Design documents` category.~~ (completed in https://github.com/apache/eventmesh-site/pull/152)

2. Older versions of the documentation should remain as they were in the Git repository at the time of each release.

Review the issue's versioned documentation and the release history in the repository, using the completed category-order change in pull request 152 as context. Determine how older-version documents are currently stored or generated, then verify that each released version remains unchanged while current documentation can still evolve.

Written by the indexing model from the issue text.