Islandora IIIF: Add labels to config schema items.

modules/islandora_iiif/config/schema/islandora_iiif.schema.yml

@@ -17,12 +17,14 @@ views.style.iiif_manifest:
   mapping:
     iiif_tile_field:
       type: sequence
+      label: "Tile source field(s)"
       sequence:
         type: string
     iiif_ocr_file_field:
       type: sequence
+      label: "Structured OCR data file field"
       sequence:
-        type: string:
+        type: string
     structured_text_term:
       type: string
       label: "Structured text term"