[DOCS] Creates page for ELSER semantic search docs (#95072)

* [DOCS] Creates page for ELSER semantic search docs.

docs/reference/search/search-your-data/search-your-data.asciidoc

@@ -527,3 +527,4 @@ include::search-shard-routing.asciidoc[]
 include::search-template.asciidoc[]
 include::sort-search-results.asciidoc[]
 include::knn-search.asciidoc[]
+include::semantic-search-elser.asciidoc[]

docs/reference/search/search-your-data/semantic-search-elser.asciidoc

@@ -0,0 +1,8 @@
+[[semantic-search-elser]]
+== Perform semantic search with ELSER
+++++
+<titleabbrev>Semantic search with ELSER</titleabbrev>
+++++
+
+:keywords: {ml-init}, {stack}, {nlp}, ELSER
+:description: ELSER is a learned sparse ranking model trained by Elastic.