Adds important callout about the possibility of multiple ELSER deploy…

…ment. (#2744) (#2745)

(cherry picked from commit b065d61)

Co-authored-by: István Zoltán Szabó <istvan.szabo@elastic.co>

docs/en/stack/ml/nlp/ml-nlp-elser.asciidoc

@@ -108,6 +108,14 @@ that walks through upgrading an index to ELSER V2.
 You can download and deploy ELSER either from **{ml-app}** > **Trained Models**, 
 from **Search** > **Indices**, or by using the Dev Console.
 
+IMPORTANT: You can deploy the model multiple times by assigning a unique
+deployment ID when starting the deployment. It enables you to have dedicated
+deployments for different purposes, such as search and ingest. By doing so, you
+ensure that the search speed remains unaffected by ingest workloads, and vice
+versa. Having separate deployments for search and ingest mitigates performance
+issues resulting from interactions between the two, which can be hard to
+diagnose.
+
 
 [discrete]
 [[trained-model]]