update README.md to better describe the cross compiler scenarios;

README.md

@@ -47,9 +47,9 @@ sudo apt-get install libasio-dev:arm64 libncurses-dev:arm64
 
 If cross-compiling is required (for either ARM 32bit, 64bit or old Raspberry Pi ARM 32bit), the CMake build system has some options:
 
-- `-DCROSS_COMPILE_ARM=1` - This will cross-compile dvmhost for ARM 32bit.
-- `-DCROSS_COMPILE_AARCH64=1` - This will cross-compile dvmhost for ARM 64bit.
-- `-DCROSS_COMPILE_RPI_ARM=1` - This will cross-compile for old Raspberry Pi ARM 32 bit. (see build notes, linked below)
+- `-DCROSS_COMPILE_ARM=1` - This will cross-compile dvmhost for generic ARM 32bit. (RPi4 running 32-bit distro's can fall into this category [on Debian/Raspian anything bullseye or newer])
+- `-DCROSS_COMPILE_AARCH64=1` - This will cross-compile dvmhost for generic ARM 64bit. (RPi4 running 64-bit distro's can fall into this category [on Debian/Raspian anything bullseye or newer])
+- `-DCROSS_COMPILE_RPI_ARM=1` - This will cross-compile for old Raspberry Pi ARM 32 bit. (typically this will be the RPi1, 2 and 3 platforms; see build notes, linked below)
 
 Please note cross-compliation requires you to have the appropriate development packages installed for your system. For ARM 32-bit, on Debian/Ubuntu OS install the "arm-linux-gnueabihf-gcc" and "arm-linux-gnueabihf-g++" packages. For ARM 64-bit, on Debian/Ubuntu OS install the "aarch64-linux-gnu-gcc" and "aarch64-linux-gnu-g++" packages.