[open] Murkmire world boss Walks-Like-Thunder not tagged with "boss1" unit tag

[silvereyes]

Most world bosses get a boss bar at the top and raise events for unitTag = boss1, boss2, etc. However, the Murkmire world boss Walks-Like-Thunder in the upper part of the map does not.

Please add the boss1 unit tag to this boss so that it raises the correct events.