Update documentation for hardware upgrade

Added notices to README.md and CHANGELOG.md about the hardware upgrade
that allows restarting the Ultra by running each RGB color once,
resolving previous firmware modification issues.

CHANGELOG.md

@@ -3,6 +3,7 @@ All notable changes to this project will be documented in this file.
 This project uses the changelog in accordance with [keepchangelog](http://keepachangelog.com/). Please use this to write notable changes, which is not the same as git commit log...
 
 ## [unreleased][unreleased]
+ - Hardware upgrade: Restarting the Ultra now only requires running each of the three RGB colors once, resolving previous firmware modification issues
  - Added commands to dump and clone Mifare tags
  - Fix bad missing tools warning (@suut)
  - Fix for FAST_READ command for nfc - mf0 tags

README.md

@@ -18,6 +18,10 @@ Guangdong, China: [MTools Tec](https://shop.mtoolstec.com/)
 
 Lazada One, Singapore: [Aliexpress by RRG](https://proxgrind.aliexpress.com/store/1101312023)
 
+# Hardware Upgrade Notice
+
+**Important:** The Chameleon Ultra hardware has been upgraded! Restarting the device now only requires running each of the three RGB colors once (equivalent to a restart). This resolves previous issues where firmware modifications could cause the device to malfunction.
+
 # What is it and how to use ?
 
 Read the [available documentation](https://github.com/RfidResearchGroup/ChameleonUltra/wiki).