Add the ET-Minion core diagram from the Erbium documentation
(aifoundry-org/erbium, Apache-2.0) and a short description of the
ET-Minion neighborhood, as suggested in review. Link the Erbium core,
interrupt, memory map and UART documentation and ET-platform, and note
that silicon uses a 10 MHz mtime while the emulator default is 2 MHz.
Signed-off-by: Afonso Oliveira <afonso.oliveira707@gmail.com>
a6cab8293d