[ot] Update top-level README file for EarlGrey branch.

Signed-off-by: Emmanuel Blot <[email protected]>

README.md

@@ -1,14 +1,15 @@
 # QEMU OpenTitan README
 
-QEMU is a generic and open source machine & userspace emulator and
-virtualizer.
+QEMU is a generic and open source machine & userspace emulator and virtualizer.
 
-QEMU is capable of emulating a complete machine in software without any
-need for hardware virtualization support. By using dynamic translation,
-it achieves very good performance.
+QEMU is capable of emulating a complete machine in software without any need for hardware
+virtualization support. By using dynamic translation, it achieves very good performance.
 
-This repository is a fork of QEMU dedicated to support Ibex and OpenTitan
-platforms.
+This branch contains a fork of QEMU 8.0.2 dedicated to support lowRISC Ibex platforms:
+  * IbexDemo with FPGA ARTY7 memory map,
+  * OpenTitan EarlGrey 2.5.2 with FPGA "Bergen Board" CW310 memory map.
+
+See [ot_ref.log](hw/opentitan/ot_ref.log) for OpenTitan reference.
 
 See [installation instructions](docs/opentitan/index.md)