Add Docker files and documentation

Dockerfile

@@ -0,0 +1,12 @@
+FROM php:7.2-cli
+
+RUN apt-get update && DEBIAN_FRONTEND=noninteractive apt-get install -y \
+    libzip-dev \
+    locales \
+    locales-all \
+    zip \
+  && docker-php-ext-configure zip --with-libzip \
+  && docker-php-ext-install zip
+
+COPY --from=composer:2 /usr/bin/composer /usr/local/bin/composer
+RUN chmod +x /usr/local/bin/composer