ice40/README.md: Reworking the README information.
ice40/README.md: Reworking the README information.

Signed-off-by: Joel Holdsworth <4816dabf8db1bc6cac35b3a24cab2ff844b5b0c7@airwebreathe.org.uk>
Signed-off-by: Tim 'mithro' Ansell <b1c1d8736f20db3fb6c1c66bb1455ed43909f0d8@mith.ro>

SymbiFlow/symbiflow-arch-defs,SymbiFlow/symbiflow-arch-defs