refactor: move Reference hardware under Reference design

[xmfcx]

Description

• Closes: Move Reference hardware under Reference design #750

How was this PR tested?

Tested by the deploy-docs workflow.

[github-actions]

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[github-actions]

Documentation URL: https://autowarefoundation.github.io/autoware-documentation/pr-751/
Modified URLs:

• https://autowarefoundation.github.io/autoware-documentation/pr-751/reference-design/
• https://autowarefoundation.github.io/autoware-documentation/pr-751/reference-design/reference-hw/ad-computers/
• https://autowarefoundation.github.io/autoware-documentation/pr-751/reference-design/reference-hw/ad_sensor_kit_suppliers/
• https://autowarefoundation.github.io/autoware-documentation/pr-751/reference-design/reference-hw/cameras/
• https://autowarefoundation.github.io/autoware-documentation/pr-751/reference-design/reference-hw/full_drivers_list/
• https://autowarefoundation.github.io/autoware-documentation/pr-751/reference-design/reference-hw/imu_ahrs_gnss_ins/
• https://autowarefoundation.github.io/autoware-documentation/pr-751/reference-design/reference-hw/
• https://autowarefoundation.github.io/autoware-documentation/pr-751/reference-design/reference-hw/lidars/
• https://autowarefoundation.github.io/autoware-documentation/pr-751/reference-design/reference-hw/radars/
• https://autowarefoundation.github.io/autoware-documentation/pr-751/reference-design/reference-hw/remote_drive/
• https://autowarefoundation.github.io/autoware-documentation/pr-751/reference-design/reference-hw/thermal_cameras/
• https://autowarefoundation.github.io/autoware-documentation/pr-751/reference-design/reference-hw/vehicle_drive_by_wire_suppliers/
• https://autowarefoundation.github.io/autoware-documentation/pr-751/reference-design/reference-hw/vehicle_platform_suppliers/