add link to logspout-fluentd
add link to logspout-fluentd

detail of how logspout-fluentd was designed : https://medium.com/magine-engineering/using-fluentd-log-driver-but-still-want-to-debug-your-container-logs-locally-try-logspout-c5b9f6ca9d07
gliderlabs/logspout,gliderlabs/logspout