Avoid the usage of raw html directives in rst files

## Context

Explore if we can remove the usage of raw html directives in rst files, by creating new custom Sphinx components.

> @dgarcia360 I want to avoid the usage of raw html in rst files.
> Is it a must? why do we need it?
> Can we move it to the theme index.html template?

_Originally posted by @tzach in https://github.com/scylladb/care-pet/issues/37#issuecomment-930019827_