Added Dockerfile and docker-compose.example.yml

docker/Dockerfile

@@ -0,0 +1,16 @@
+FROM openjdk:18
+
+ENV GAMEYFIN_ROOT=/opt/gameyfin-library
+
+RUN groupadd gameyfin && useradd gameyfin -g gameyfin && \
+    mkdir -p /opt/gameyfin ${GAMEYFIN_ROOT} && \
+    chown -R gameyfin:gameyfin /opt/gameyfin ${GAMEYFIN_ROOT}
+
+USER gameyfin:gameyfin
+
+ARG JAR_FILE=./backend/target/*.jar
+COPY ${JAR_FILE} /opt/gameyfin/gameyfin.jar
+
+WORKDIR /opt/gameyfin
+
+ENTRYPOINT ["java", "-Dspring.config.name=application,gameyfin,database,secure", "-jar", "gameyfin.jar"]