Mention support for Pi 4

README.md

@@ -1,6 +1,6 @@
 # Introduction
 
-This repository implements a driver for certain SPI-based LCD displays for Raspberry Pi A, B, 2, 3 and Zero.
+This repository implements a driver for certain SPI-based LCD displays for Raspberry Pi A, B, 2, 3, 4 and Zero.
 
 ![PiTFT display](/example.jpg "Adafruit PiTFT 2.8 with ILI9341 controller")
 
@@ -156,7 +156,7 @@ There are a couple of options to explicitly say which Pi board you want to targe
 - `-DSINGLE_CORE_BOARD=ON`: Pass this option if you are running on a Pi that has only one hardware thread (Pi Model A, Pi Model B, Compute Module 1, Pi Zero/Zero W). If not present, autodetected.
 - `-DARMV6Z=ON`: Pass this option to specifically optimize for ARMv6Z instruction set (Pi 1A, 1A+, 1B, 1B+, Zero, Zero W). If not present, autodetected.
 - `-DARMV7A=ON`: Pass this option to specifically optimize for ARMv7-A instruction set (Pi 2B < rev 1.2). If not present, autodetected.
-- `-DARMV8A=ON`: Pass this option to specifically optimize for ARMv8-A instruction set (Pi 2B >= rev. 1.2, 3B, 3B+, CM3 or CM3 lite). If not present, autodetected.
+- `-DARMV8A=ON`: Pass this option to specifically optimize for ARMv8-A instruction set (Pi 2B >= rev. 1.2, 3B, 3B+, CM3, CM3 lite or 4B). If not present, autodetected.
 
 ###### Specifying other build options