Fixes

Fixes #51 by @A91y

Description

Added a text copy button to copy all text on the page

Technical details

The feature is added by adding a floating button on the top of screen, which falicitates copying using js.

Checklist

• My pull request has a descriptive title (not a vague title like Update index.md).
• My pull request targets the default branch of the repository (main or master).
• My commit messages follow best practices.
• My code follows the established code style of the repository.
• I tried running the project locally and verified that there are no
  visible errors.