Update Getting started with RISC-V

[anarchitech]

The instructions for using muforth in Getting started with RISC-V are out of date. The use of openocd is no longer required.

To chat with a target (we'll use the HiFive1 as an example,) use the relevant patched code referenced here until the changes get incorporated into origin/master.

NB: This patch did not add this code, it simply fixes some malfeasance that crept in with changes to asm{{ & }}.

NB: Make sure muforth/mu/serial-target is symlinked to the correct /dev/whateva! On OpenBSD, this is /dev/cuaU1. Make sure you are a member of the group for that device! On OpenBSD, this is group dialer.

cd muforth/mu
./muforth -f target/RISC-V/board/hifive1.mu4
chat

and you should be good to go.