Delete "UCL" as allowed value in @subtype on TEI:label

[davidamichelson]

@dlschwartz @wlpotter

I made the update to the table: b4d3bc5

One question, I don't see "UCL" in the data anymore, should we remove it from the schema or did I miss something?

[wlpotter]

I think we thought these were University College London, but they turned out to be Cambridge (University of Cambridge Library), and got the subtype of "Cambridge" instead