Update README.TXT

README.TXT

@@ -3,7 +3,7 @@ WiringPi (Rhizomatica's Fork)
 
 This is an unofficial fork of wiringPi to support newer Linux distributions.  With the
 [end of official development](https://web.archive.org/web/20220405225008/http://wiringpi.com/wiringpi-deprecated/), this repository
-has become our fork of a working WiringPi version for all versions of Debian Linux (and all Raspberries Pi up to and including version 4). Raspberry Pi 5 is not yet supported.
+has become our fork of a working WiringPi version for all versions of Debian Linux, and all Raspberries Pi up to and including version 4 (for Raspberry Pi 1 or early 2 revisions, edit wiringPi/wiringPi.c and change gpioLayout to 1). Raspberry Pi 5 is not yet supported.
 
   * The final "official" source release can be found at the
     [`final_source_2.50`](https://github.com/WiringPi/WiringPi/tree/final_official_2.50) tag.