Update WHATS_NEW_RRF3.md

WHATS_NEW_RRF3.md

@@ -7,11 +7,13 @@ Recommended compatible firmware:
 - DuetSoftwareFramework 1.2.2.0
 - Duet3Firmware_EXP3HC 3.0
 
-Upgrade notes since beta12:
+Upgrade notes:
+- **If you are upgrading from RepRapFirmware 2.x then you will need to make substantial changes to your config.g file.** See https://duet3d.dozuki.com/Wiki/RepRapFirmware_3_overview#Section_Summary_of_what_you_need_to_do_to_convert_your_configuration_and_other_files for details.
+
+The remaining items affect users of RepRapFirmware 3.0 beta (but not RC) versions:
 - Endstop type S0 (active low switch) is no longer supported in M574 commands. Instead, use type S1 and invert the input by prefixing the pin name with '!'.
 - If you are using Duet 3 expansion or tool boards, you must upgrade those to 3.0 too
-- Duet 3+SBC users must use DSF 1.2.2.0 or a compatible later version with this version of RRF
-- You should also upload the new IAP file for your system. You will need it when upgrading firmware in future. These files are called Duet2CombinedIAP.bin, DuetMaestroIAP.bin, Duet3_SBCiap_MB6HC.bin (for Duet 3+SBC) and Duet3_SDiap.bin (for Duet 3 standalone systems). You can leave the old IAP files on your system, they have different names and you will need them if you downgrade to earlier firmware.
+- You should also upload the new IAP file for your system. You will need it when upgrading firmware in future. These files are called Duet2CombinedIAP.bin, DuetMaestroIAP.bin, Duet3_SBCiap_MB6HC.bin (for Duet 3+SBC) and Duet3_SDiap.bin (for Duet 3 standalone systems). Leave the old IAP files on your system, they have different names and you will need them again if you downgrade to older firmware.
 - Duet 3 users: there is no longer a default bed heater. To use Heater 0 as the bed heater, put M140 H0 in config.g (later in config.g than your M950 H0 command).
 
 Known limitations: