* Add a temporary README file

This commit adds a temporary readme file that points users to the
main README file or the User Guide.

* Add a "getting started" doc

This commit adds a page for getting started, copying the
"Get started now" from the current `README.md`.

* Add link to the get started page from the index page

* Add the getting started doc to the site header

* Add footer link to getting started info

* Add getting started to the sidebar

* Add placeholder for the user guide page

* Add links to the user-guide page as well

* Add auto-generated i18n file

* Move all docusaurus related files into own folder