Updating retriever-examples documentation to run validation tests on the provided snippets

docs/build.gradle

@@ -1440,6 +1440,95 @@ setups['calendar_outages_addevent'] = setups['calendar_outages_addjob'] + '''
            ]}
 '''
 
+// Used by the retrievers-examples
+  buildRestTests.setups['retrievers_examples'] = '''
+  - do:
+      raw:
+        method: PUT
+        path: "retrievers_example"
+        body: |
+          {
+             "mappings": {
+                 "properties": {
+                     "vector": {
+                         "type": "dense_vector",
+                         "dims": 3,
+                         "similarity": "l2_norm",
+                         "index": true
+                     },
+                     "text": {
+                         "type": "text"
+                     },
+                     "year": {
+                         "type": "integer"
+                     },
+                     "topic": {
+                         "type": "keyword"
+                     }
+                 }
+             }
+          }
+  - do:
+      raw:
+        method: POST
+        path: "retrievers_example/_doc/1"
+        body: |
+          {
+           "vector": [0.23, 0.67, 0.89],
+           "text": "Large language models are revolutionizing information retrieval by boosting search precision, deepening contextual understanding, and reshaping user experiences in data-rich environments.",
+           "year": 2024,
+           "topic": ["llm", "ai", "information_retrieval"]
+          }
+  - do:
+      raw:
+        method: POST
+        path: "retrievers_example/_doc/2"
+        body: |
+          {
+           "vector": [0.12, 0.56, 0.78],
+           "text": "Artificial intelligence is transforming medicine, from advancing diagnostics and tailoring treatment plans to empowering predictive patient care for improved health outcomes.",
+           "year": 2023,
+           "topic": ["ai", "medicine"]
+          }
+  - do:
+      raw:
+        method: POST
+        path: "retrievers_example/_doc/3"
+        body: |
+          {
+           "vector": [0.45, 0.32, 0.91],
+            "text": "AI is redefining security by enabling advanced threat detection, proactive risk analysis, and dynamic defenses against increasingly sophisticated cyber threats.",
+           "year": 2024,
+           "topic": ["ai", "security"]
+          }
+  - do:
+      raw:
+        method: POST
+        path: "retrievers_example/_doc/4"
+        body: |
+          {
+           "vector": [0.34, 0.21, 0.98],
+           "text": "Elastic introduces Elastic AI Assistant, the open, generative AI sidekick powered by ESRE to democratize cybersecurity and enable users of every skill level.",
+           "year": 2023,
+           "topic": ["ai", "elastic", "assistant"]
+          }
+  - do:
+      raw:
+        method: POST
+        path: "retrievers_example/_doc/5"
+        body: |
+          {
+           "vector": [0.11, 0.65, 0.47],
+           "text": "Learn how to spin up a deployment of our hosted Elasticsearch Service and use Elastic Observability to gain deeper insight into the behavior of your applications and systems.",
+           "year": 2024,
+           "topic": ["documentation", "observability", "elastic"]
+          }
+  - do:
+      raw:
+        method: POST
+        path: "retrievers_example/_refresh"
+'''
+
 // used by median absolute deviation aggregation
 setups['reviews'] = '''
   - do: