Fix documentation to point to the consumer-grade SoC
The DevKit, Birch and Chestnut documentation pages say:
Customer grade i.MX 8M Quad [datasheet] and [reference manual]
The linked datasheet is for the industrial-grade i.MX8 8M Quad which runs at 1.3GHz, but the Librem 5 is using the consumer-grade i.MX8 8M Quad which runs at 1.5GHz.
This should be changed to:
Consumer grade i.MX 8M Quad [datasheet] and [reference manual]
(login with an email address that doesn't contain @gmail, @yahoo or @hotmail is required to download the reference manual)