add required allow-free-text fields for schema validation

Author: qqmyers

examples/config/cvoc-conf.singlevocab.json

@@ -6,6 +6,7 @@
         "protocol": "skosmos",
         "retrieval-uri": "https://skosmos.dev.finto.fi/rest/v1/data?uri={0}",
         "term-parent-uri": "",
+        "allow-free-text": false,
         "languages":"en, fr, es, ru",
         "vocabs": {
             "unesco": {
@@ -87,6 +88,7 @@
         "js-url": "https://gdcc.github.io/dataverse-external-vocab-support/scripts/skosmos.js",
         "protocol": "skosmos",
         "retrieval-uri": "https://skosmos.dev.finto.fi/rest/v1/data?uri={0}",
+        "allow-free-text": false,
         "languages":"en, uk, fr, ru",
         "vocabs":{
             "unesco": {