* Update shortcuts.md

Removed content that was out-of-date and redundant with the UI.

* Added panels.md

* Added dashboards.md

* Added data-sources.md

* Update data-sources.md

* Sorted basic concepts into other topics

* Update docs/sources/menu.yaml

Co-Authored-By: Marcus Olsson <accounts+github@marcus.se.net>

* Update panels.md

* Update data-sources.md

Co-authored-by: Marcus Olsson <accounts+github@marcus.se.net>