Add Julien's blog post to the README. (#425)

Signed-off-by: Tom Wilkie <tom.wilkie@gmail.com>

README.md

@@ -55,11 +55,13 @@ Your feedback is always welcome.
 ## Further Reading
 
 - The original [design doc](https://docs.google.com/document/d/11tjK_lvp1-SVsFZjgOTr1vV3-q6vBAsZYIQ5ZeYBkyM/view) for Loki is a good source for discussion of the motivation and design decisions.
+- Julien Garcia Gonzalez' March 2019 blog post "[Grafana Logging using Loki][giant-swarm-blog]".
 - Tom Wilkie's early-2019 CNCF Paris/FODEM talk "[Grafana Loki: like Prometheus, but for logs][fosdem19-talk]" ([slides][fosdem19-slides], [video][fosdem19-video]).
 - David Kaltschmidt's KubeCon 2018 talk "[On the OSS Path to Full Observability with Grafana][kccna18-event]" ([slides][kccna18-slides], [video][kccna18-video]) on how Loki fits into a cloud-native environment.
 - Goutham Veeramachaneni's blog post "[Loki: Prometheus-inspired, open source logging for cloud natives](https://grafana.com/blog/2018/12/12/loki-prometheus-inspired-open-source-logging-for-cloud-natives/)" on details of the Loki architectire.
 - David Kaltschmidt's blog post "[Closer look at Grafana's user interface for Loki](https://grafana.com/blog/2019/01/02/closer-look-at-grafanas-user-interface-for-loki/)" on the ideas that went into the logging user interface.
 
+[giant-swarm-blog]: https://blog.giantswarm.io/grafana-logging-using-loki
 [fosdem19-talk]: https://fosdem.org/2019/schedule/event/loki_prometheus_for_logs/
 [fosdem19-slides]: https://speakerdeck.com/grafana/grafana-loki-like-prometheus-but-for-logs
 [fosdem19-video]: https://mirror.as35701.net/video.fosdem.org/2019/UB2.252A/loki_prometheus_for_logs.mp4