Vitepress docs

[ArtyomVancyan]

Motivation:

In the suggested changes, there is the implementation of the complete Markdown documentation powered by VitePress. Apart from the documentation there was improved a small feature that allows accessing user attributes with __getattr__ and tests for that also have been added.

All Submissions:

• Have you followed the guidelines in our Contributing document?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?

Changes to Core Features:

• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you updated the documentation related to the changes you have made?
• Have you written new tests for your core changes, as applicable?
• Have you successfully run tests with your changes locally?