clarify "opennlp evaluation test data" in opennlp-dl/README.md (#560)

* clarify "opennlp evaluation test data" in opennlp-dl/README.md

* Update opennlp-dl/README.md

Author: cpoerschke

opennlp-dl/README.md

@@ -4,7 +4,7 @@ This module provides OpenNLP interface implementations for ONNX models using the
 
 **Important**: This does not provide the ability to train models. Model training is done outside of OpenNLP. This code provides the ability to use ONNX models from OpenNLP.
 
-Models used in the tests are available in the opennlp evaluation test data.
+Models used in the tests are available in the [opennlp evaluation test data](https://nightlies.apache.org/opennlp/opennlp-data.zip) location.
 
 ## NameFinderDL
 
@@ -50,4 +50,4 @@ tokenizer = AutoTokenizer.from_pretrained(model_id)
 # save onnx checkpoint and tokenizer
 model.save_pretrained(onnx_path)
 tokenizer.save_pretrained(onnx_path)
-```
+```