[DOCS] Adds testing ELSER section to ELSER conceptual (#2540) (#2541)

(cherry picked from commit 87a482c)

Co-authored-by: István Zoltán Szabó <[email protected]>

Author: mergify[bot]

docs/en/stack/ml/nlp/images/ml-nlp-elser-test.png

@@ -314,6 +314,26 @@ xpack.ml.model_repository: file://${path.home}/config/models/`
 master-eligible nodes one by one.
 
 
+[discrete]
+== Testing ELSER
+
+You can test the deployed model in {kib}. Navigate to **Model Management** > 
+**Trained Models**, locate the deployed ELSER model in the list of trained 
+models, then select **Test model** from the Actions menu.
+
+You can use data from an existing index to test the model. Select the index, 
+then a field of the index you want to test ELSER on. Provide a search query and 
+click **Test**. Evaluating model recall is simpler when using a query related to 
+the documents.
+
+The results contain a list of ten random values for the selected field along 
+with a score showing how relevant each document is to the query. The higher the 
+score, the more relevant the document is.
+
+[role="screenshot"]
+image::images/ml-nlp-elser-test.png[alt="Testing ELSER",align="center"]
+
+
 [discrete]
 [[further-readings]]
 == Further reading