doc: update build doc and add script for docker (#1204)

build/build_docker.sh

@@ -0,0 +1,29 @@
+#!/bin/bash
+
+exists() { type -t "$1" > /dev/null 2>&1; }
+
+rm -rf VSCode*
+rm -rf vscode*
+
+if ! exists yarn; then
+  curl -fsSL https://deb.nodesource.com/setup_16.x | sudo -E bash -
+  sudo apt-get install -y nodejs desktop-file-utils
+
+  npm install -g yarn
+fi
+
+UNAME_ARCH=$( uname -m )
+
+if [[ "${UNAME_ARCH}" == "x86_64" ]]; then
+  export VSCODE_ARCH="x64"
+else
+  export npm_config_arch=armv7l
+  export npm_config_force_process_config="true"
+  export VSCODE_ARCH="armhf"
+fi
+
+echo "-- VSCODE_ARCH: ${VSCODE_ARCH}"
+
+. get_repo.sh
+
+SHOULD_BUILD=yes CI_BUILD=no OS_NAME=linux . build.sh