Add indications for cross building

cross/aarch64-linux.Dockerfile

@@ -0,0 +1,15 @@
+FROM ghcr.io/cross-rs/aarch64-unknown-linux-gnu:main
+
+RUN dpkg --add-architecture arm64 && \
+    apt-get update && \
+    apt-get install -y --no-install-recommends \
+        cmake \
+        libclang-dev \
+        libasound2-dev:arm64 \
+        libjack-dev:arm64 \
+        libxcb-render0-dev:arm64 \
+        libxcb-shape0-dev:arm64 \
+        libxcb-xfixes0-dev:arm64 \
+        libxkbcommon-dev:arm64 \
+        libgl1-mesa-dev:arm64 \
+    && rm -rf /var/lib/apt/lists/*