Add libreoffice export

Dockerfile

@@ -24,7 +24,10 @@ ENV NODE_ENV=production
 #
 # Running as non-root enables running this image in platforms like OpenShift
 # that do not allow images running as root.
-RUN useradd --uid 5001 --create-home etherpad
+RUN useradd --uid 5001 --create-home etherpad && \
+	mkdir -p /usr/share/man/man1
+
+RUN apt-get update && apt-get install -y libreoffice
 
 RUN mkdir /opt/etherpad-lite && chown etherpad:0 /opt/etherpad-lite
 
@@ -50,5 +53,6 @@ COPY --chown=etherpad:0 ./settings.json.docker /opt/etherpad-lite/settings.json
 # Fix permissions for root group
 RUN chmod -R g=u .
 
+ENV SOFFICE=/usr/bin/soffice
 EXPOSE 9001
 CMD ["node", "node_modules/ep_etherpad-lite/node/server.js"]