This indicates players who have donated their free time to assist the development of the shard in a variety of ways. Such as video editing, historical research, bug testing, patch testing, helping isolate specific bugs, and verify their resolution. These players on multiple occasions have been available to test tedious and boring things to make sure that our patches are successful. As we do not reward players ingame, this is our way of saying thanks to players that help make Renaissance great. Coming soon this will be the marker for our companion program in which players can donate their time to assist new players in becoming acclimated to the shard.
Thanks for answering Chris. That raises a second question: Where's the sign-up sheet? I've been reporting bugs and historical data independently almost since I started playing here; it would be great to do it as part of a joint/focused effort, and not just for a yellow board name. I just really never knew this was going on.