Update README.md

Removed 6.20 support for 09g

Author: TheZett

README.md

@@ -12,6 +12,7 @@ The downgrader is "signed", and can be launched without having a custom firmware
 ### Version 7.2
 * Removed 'factory firmware limitation', which prevented certain PSPs from being downgradable at all or limited them from being downgraded to certain firmwares they theoretically support.
 * Chronoswitch now detects your PSP's motherboard alongside its model and allows flashing all firmwares (5.00+) that are supported by it.
+* Removed support for downgrading 09g units below 6.30.
 ### Version 7.1
 * Added experimental support for 07g units on 6.6x.
 ### Version 7.0