Add image source label to dockerfiles (#573)

* Update Dockerfile

* Update debian.Dockerfile

Author: wuast94

Dockerfile

@@ -28,6 +28,7 @@ RUN yarn install --pure-lockfile --production
 FROM base
 
 LABEL maintainer="Grafana team <[email protected]>"
+LABEL org.opencontainers.image.source="https://github.com/grafana/grafana-image-renderer"
 
 ARG GF_UID="472"
 ARG GF_GID="472"

debian.Dockerfile

@@ -33,6 +33,7 @@ RUN yarn install --pure-lockfile --production
 
 # Final stage
 FROM base
+LABEL org.opencontainers.image.source="https://github.com/grafana/grafana-image-renderer"
 
 ENV NODE_ENV=production