Add PromCon live streaming and Twitter to news banner
Add PromCon live streaming and Twitter to news banner

Signed-off-by: Julius Volz <d7748b1e6f41fd74500c5ccae0980eab88c2ef61@gmail.com>

ddfreyne/prometheus-docs,prometheus/docs,ddfreyne/prometheus-docs,prometheus/docs,ddfreyne/prometheus-docs,prometheus/docs,ddfreyne/prometheus-docs