allow values "valley" and "cemetery" for @type attribute on tei:place elements

[wlpotter]

allow values "valley" and "cemetery" for @type attribute on tei:place elements. A related issue will address updating the documentation and place-type lists for these two new place types. See, https://bqgazetteer.bethmardutho.org/place/5045 for an example of "cemetery" and https://bqgazetteer.bethmardutho.org/place/5518 for an example of "valley".

@dlschwartz I believe we will want to port this to the Syriaca schema as we are ingesting some of these place types from the BQG records to the Syriac Gazetteer.

As for the comment here:

@wlpotter @davidamichelson I've been thinking that our place types should get URIs instead of the status quo. Would this be a time to make that change or should we simply update the current list and move everything to URIs down the line when the taxonomy develops?

We may update the place-types to URIs for the syriaca schema, but I think it might be easiest just to add these two place type values for the BQG-specific schema. @davidamichelson thoughts?

[dlschwartz]

I think this can be closed.