Add DocFX site generator skeleton

docs/Dockerfile

@@ -0,0 +1,22 @@
+FROM mono:latest
+
+RUN apt-get update -y && apt-get install -y unzip
+
+RUN mkdir -p /docfx
+WORKDIR /docfx
+RUN curl -L https://github.com/dotnet/docfx/releases/download/v2.43.3/docfx.zip -O \
+  && unzip docfx.zip \
+  && chmod +r /docfx
+
+RUN echo "#!/bin/bash" >> /usr/local/bin/docfx \
+   && echo "mono /docfx/docfx.exe \"\$@\"" >> /usr/local/bin/docfx \
+   && chmod +x /usr/local/bin/docfx
+
+RUN mkdir -p /srv/project \
+  && useradd -u 1000 docfx \
+  && chown docfx:docfx /srv/project
+
+USER docfx
+WORKDIR /srv/project
+
+ENTRYPOINT ["docfx"]