replace broken link

Author: rmseifried

docs/validate-metadata.md

@@ -1,7 +1,7 @@
 
 # Validating metadata
 
-Once the metadata records are in the OpenGeoMetadata format, they should be validated to make sure the fields are correctly formatted. The current version of the schema is available as a [JSON-Schema file](https://github.com/geoblacklight/geoblacklight/blob/master/schema/geoblacklight-schema.json). This file format provides support for data validation with the [JSON Schema Vocabulary](http://json-schema.org).
+Once the metadata records are in the OpenGeoMetadata format, they should be validated to make sure the fields are correctly formatted. The current version of the schema is available as a [JSON-Schema file](https://github.com/geoblacklight/geoblacklight/blob/main/schema/geoblacklight-schema-aardvark.json). This file format provides support for data validation with the [JSON Schema Vocabulary](http://json-schema.org).
 
 
 Use [GeoCombine](https://github.com/OpenGeoMetadata/GeoCombine), which has a [.valid? method](http://www.rubydoc.info/gems/geo_combine/0.1.0/GeoCombine/GeoBlacklight#valid%3F-instance_method) that makes using these tools simple.