doc: move and rename loaders section

PR-URL: #49261 Backport-PR-URL: #50669 Reviewed-By: Matteo Collina <[email protected]> Reviewed-By: Jacob Smith <[email protected]> Reviewed-By: Rafael Gonzaga <[email protected]> Reviewed-By: Benjamin Gruenbaum <[email protected]>

Author: GeoffreyBooth