[Docker] Add support for arm32/64 (#2104)

hooks/build

@@ -0,0 +1,10 @@
+#!/bin/bash
+
+# Custom build script to build images for all supported architectures.
+# Example for IMAGE_NAME: rss-builder/rss-builder:stable
+
+for arch in amd64 arm32v7 arm64v8
+do
+  echo "Building $IMAGE_NAME-$arch"
+  docker build --build-arg FROM_ARCH=$arch --file $DOCKERFILE_PATH --tag $IMAGE_NAME-$arch .
+done