Support docker

Dockerfile

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+ FROM debian:buster-slim
+
+ RUN apt update && \
+     apt install -y git make gcc libssl-dev && \
+     git clone https://github.com/pymumu/smartdns.git --depth 1 && \
+     cd smartdns && \
+     sh ./package/build-pkg.sh --platform debian --arch `dpkg --print-architecture` && \
+     dpkg -i package/*.deb && \
+     cd / && \
+     rm -rf smartdns/ && \
+     apt autoremove -y git make gcc libssl-dev && \
+     apt clean && \
+     rm -rf /var/lib/apt/lists/*
+
+ EXPOSE 53/udp
+ VOLUME "/etc/smartdns/"
+
+ CMD ["/usr/sbin/smartdns", "-f"]