added OCI docker labels (#4996)

.docker/Dockerfile.kimai-base

@@ -167,8 +167,6 @@ HEALTHCHECK --interval=20s --timeout=10s --retries=3 \
 FROM ${BASE}-base AS base
 ARG TIMEZONE
 
-LABEL maintainer="tobias@neontribe.co.uk"
-
 ENV TIMEZONE=${TIMEZONE}
 RUN ln -snf /usr/share/zoneinfo/${TIMEZONE} /etc/localtime && echo ${TIMEZONE} > /etc/timezone && \
     # make composer home dir

Dockerfile

@@ -47,7 +47,17 @@ FROM ${BASE}-base AS base
 ARG KIMAI
 ARG TIMEZONE
 
-LABEL maintainer="tobias@neontribe.co.uk"
+LABEL org.opencontainers.image.title="Kimai" \
+      org.opencontainers.image.description="Kimai is a time-tracking application." \
+      org.opencontainers.image.authors="Kimai Community" \
+      org.opencontainers.image.url="https://www.kimai.org/" \
+      org.opencontainers.image.documentation="https://www.kimai.org/documentation/" \
+      org.opencontainers.image.source="https://github.com/kimai/kimai" \
+      org.opencontainers.image.version="${KIMAI}" \
+      org.opencontainers.image.revision="${{github.sha}}" \
+      org.opencontainers.image.vendor="Kevin Papst" \
+      org.opencontainers.image.licenses="AGPL-3.0" \
+      org.opencontainers.image.base.name="docker.io/library/alpine"
 
 ENV KIMAI=${KIMAI}
 ENV TIMEZONE=${TIMEZONE}