Minor cleanup

docker/Dockerfile.viewer

@@ -100,7 +100,7 @@ RUN apt-get update && \
     apt-get clean
 
 # Install Python requirements
-ADD requirements/requirements.viewer.txt /tmp/requirements.txt
+COPY requirements/requirements.viewer.txt /tmp/requirements.txt
 RUN pip install --no-cache-dir -r /tmp/requirements.txt
 
 # Works around issue with `curl`

webview/Dockerfile

@@ -5,6 +5,7 @@ FROM --platform=linux/arm/v7 balenalib/rpi-raspbian:buster as builder
 # to make things work.
 RUN apt-get update && \
     apt-get install -y \
+        apt-utils \
         firebird-dev \
         freetds-dev \
         gstreamer-tools \

webview/README.md

@@ -4,7 +4,7 @@ Since our entire build environment resides inside a Docker container, you don't
 
 ```
 $ cd webview
-$ docker build \
+$ docker buildx build \
     --build-arg GIT_HASH=$(git rev-parse --short HEAD) \
     -t qt-builder .
 ```