Minor tweaks to README.md

Few tweaks based on a newcomers experience getting an Arty A7-100 up and running

Forgot to add DCO in initial PR, now corrected.

Signed-off-by: Hugh Blemings <hugh@blemings.org>

README.md

@@ -12,6 +12,8 @@ to understand.
 <img src="http://neuling.org/microwatt-micropython.gif" alt="MicroPython running on Microwatt"/>
 </p>
 
+You can try out Microwatt/Micropython without hardware by using the ghdl simulator. If you want to build directly for a hardware target board, see below.
+
 - Build micropython. If you aren't building on a ppc64le box you
   will need a cross compiler. If it isn't available on your distro
   grab the powerpc64le-power8 toolchain from https://toolchains.bootlin.com
@@ -70,11 +72,12 @@ cd microwatt-fusesoc
 fusesoc library add microwatt /path/to/microwatt/
 ```
 
-- Build using FuseSoC. For hello world (Replace nexys_video with your FPGA board):
+- Build using FuseSoC. For hello world (Replace nexys_video with your FPGA board such as --target=arty_a7-100):
 
 ```
 fusesoc run --target=nexys_video microwatt --memory_size=8192 --ram_init_file=/path/to/microwatt/fpga/hello_world.hex
 ```
+You should then be able to see output via the serial port of the board (/dev/ttyUSB1, 115200 for example assuming standard clock speeds). There is a know bug where initial output may not be sent - try the reset (not programming button on your board if you don't see anything.
 
 - To build micropython (currently requires 1MB of BRAM eg an Artix-7 A200):