Allow linking to the latest documentation with the specific version

This is more of a "hosting the documentation" kind of issue, and might not be the right place for it. But thought to report it here anyway, since it seems to affect just Barman cloud plugin and I couldn't figure out a better place for it.

Currently it isn't possible to link to the latest plugin version documentation with a version specific link. I.e.
- works
- does not work
- works

This means that when writing documentation like "here's the list of relevant documentation on different software we're using", one can't link to the correct version. Which leads to documentation like "remember to double check that the documentation version matches the version on the list!".

未指定文件、测试或入口点。首先复现可用和失效的文档 URL，并找到按版本划分的 Barman Cloud 插件文档的托管配置。当最新的插件版本（包括 0.9.0）可以通过特定版本的文档链接访问时，即视为完成。

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