For an extant tag wiki:
To edit this wiki, you must have at least 2000 reputation and hold the bronze tag badge for this tag.
To begin a tag wiki:
Tag wikis can be edited by users with more than 1500 reputation, provided:
They are in the top 20 answerers for this tag
They hold the bronze tag badge for this tag
For such a (relatively) young, small and low-traffic site, those thresholds seem a bit high. At the time of writing, there are only 35 users with rep ≥ 1500, 25 with rep ≥ 2000, and 6 with tag badges. Hardly in the “wiki” spirit?