Should update theme/docsy step by step to the latest docsy

Currently `kubernetes/website` uses `google/docsy` as the theme with version `v0.2.0` as following:

https://github.com/kubernetes/website/blob/cc7c09d026ff7e932cdf1f93578b86cadc423a59/.gitmodules#L1-L4

However, some of the non-fixed styling issues in #43740 will be fixed by the theme itself, please reference the releases here:

https://github.com/google/docsy/releases, docsy is currently at v0.7.2 right now.

Besides the non-fixed-styling issues, there are so many vulnerabilities updates that docsy have made for and bumped versions of dependencies for, I think `kubernetes/website` should take some time and get this repository updated with the theme it uses progressively and continually.