cross compile + android jdk note

Signed-off-by: lizzie <lizzie@eden-emu.dev>

docs/CrossCompile.md

@@ -0,0 +1,10 @@
+# Cross Compile
+
+## ARM64
+
+A painless guide for cross compilation (or to test NCE) from a x86_64 system without polluting your main.
+
+- Install QEMU: `sudo pkg install qemu`
+- Download Debian 13: `wget https://cdimage.debian.org/debian-cd/current/arm64/iso-cd/debian-13.0.0-arm64-netinst.iso`
+- Create a system disk: `qemu-img create -f qcow2 debian-13-arm64-ci.qcow2 30G`
+- Run the VM: `qemu-system-aarch64 -M virt -m 2G -cpu max -bios /usr/local/share/qemu/edk2-aarch64-code.fd -drive if=none,file=debian-13.0.0-arm64-netinst.iso,format=raw,id=cdrom -device scsi-cd,drive=cdrom -drive if=none,file=debian-13-arm64-ci.qcow2,id=hd0,format=qcow2 -device virtio-blk-device,drive=hd0 -device virtio-gpu-pci -device usb-ehci -device usb-kbd -device intel-hda -device hda-output -nic user,model=virtio-net-pci`

docs/README.md

@@ -3,6 +3,7 @@
 This contains documentation created by developers. This contains build instructions, guidelines, instructions/layouts for [cool stuff we made](./CPMUtil), and more.
 
 - **[General Build Instructions](Build.md)**
+- **[Cross Compiling](CrossCompile.md)**
 - **[Development Guidelines](Development.md)**
 - **[Dependencies](Deps.md)**
 - **[Debug Guidelines](./Debug.md)**

docs/build/Android.md

@@ -35,6 +35,8 @@ Eden by default will be cloned into -
 6. To build the optimised build use `./gradlew assembleGenshinSpoofRelWithDebInfo`.
 7. You can pass extra variables to cmake via `-PYUZU_ANDROID_ARGS="-D..."`
 
+Remember to have a Java SDK installed if not already, on Debian and similar this is done with `sudo apt install openjdk-17-jdk`.
+
 ### Script
 A convenience script for building is provided in `.ci/android/build.sh`. The built APK can be put into an `artifacts` directory via `.ci/android/package.sh`. On Windows, these must be done in the Git Bash or MinGW terminal.