Add minor improvements for DFN-8-1EP_2x2mm_P0.5mm_EP0.6x1.2mm
This MR just slightly improves the source datasheet: one specific for the package rather than for a part that happens to use this package. The same datasheet is being referenced by the 3D package:
Previous datasheet: https://www.onsemi.com/pub/Collateral/NUF4401MN-D.PDF#page=6 New datasheet: https://www.onsemi.com/pub/Collateral/506AQ.PDF
And it adds a MPN under which it seems to be known: 506AQ.
This only changes metadata.