Make contrib.

Author: szabosteve

specification/_doc_ids/table.csv

@@ -823,6 +823,7 @@ test-grok-pattern,https://www.elastic.co/guide/en/elasticsearch/reference/{branc
 time-value,https://github.com/elastic/elasticsearch/blob/{branch}/libs/core/src/main/java/org/elasticsearch/core/TimeValue.java
 time-zone-id,https://docs.oracle.com/javase/8/docs/api/java/time/ZoneId.html
 trim-processor,https://www.elastic.co/guide/en/elasticsearch/reference/current/trim-processor.html
+unfreeze-index-api,https://www.elastic.co/guide/en/elasticsearch/reference/{branch}/unfreeze-index-api.html
 update-dfanalytics,https://www.elastic.co/docs/api/doc/elasticsearch/operation/operation-ml-update-data-frame-analytics
 update-desired-nodes,https://www.elastic.co/docs/api/doc/elasticsearch/group/endpoint-cluster
 update-license,https://www.elastic.co/docs/api/doc/elasticsearch/operation/operation-license-post