[gnome-build-meta.wiki] Update risc v - add SiFive instructions

[Sam Thursfield <sthursfield src gnome org>]

commit aafd1a5c590815958d8bf02e4a3a60368162bc9b
Author: Sam Thursfield <sam afuera me uk>
Date:   Fri Oct 1 09:39:37 2021 +0000

    Update risc v - add SiFive instructions

 risc-v.md | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)
---
diff --git a/risc-v.md b/risc-v.md
index 46ab76a..8706949 100644
--- a/risc-v.md
+++ b/risc-v.md
@@ -1,3 +1,5 @@
+## Instructions for QEMU
+
 ### Build
 
 ```
@@ -26,4 +28,12 @@ qemu-img resize disk.qcow2 50G
 
 ```
 qemu-system-riscv64 -M virt -m 16G -smp 8 -bios 
firmware/usr/share/opensbi/lp64/generic/firmware/fw_payload.elf -drive file=disk.qcow2,format=qcow2,if=virtio 
-display spice-app,gl=on -device virtio-gpu,xres=1920,yres=1080 -device usb-ehci -device usb-kbd -device 
usb-tablet -netdev user,id=n1 -device virtio-net-pci,netdev=n1 -soundhw hda
-```
\ No newline at end of file
+```
+
+## Instructions for SiFive Unmatched
+
+As above, but following [!5046](https://gitlab.com/freedesktop-sdk/freedesktop-sdk/-/merge_requests/5046/):
+
+* Build and flash `vm/firmware/bootloader-unmatched.bst` to an sd-card. Put it in the sd card reader of the 
board.
+* Flash `vm/minimal/efi.bst` or `vm/desktop/efi.bst` to NVMe or to a USB storage device. And add the device 
to the board.
+* Press the power button.
\ No newline at end of file