[Backport 8.15] Added/updated snippets for docs (#2319)

(cherry picked from commit f737290d10)

Co-authored-by: Josh Mock <joshua.mock@elastic.co>

docs/doc_examples/be9376b1e354ad9c6bdad83f6a0ce5ad.asciidoc

@@ -0,0 +1,61 @@
+// This file is autogenerated, DO NOT EDIT
+// Use `node scripts/generate-docs-examples.js` to generate the docs examples
+
+[source, js]
+----
+const response = await client.transform.previewTransform({
+  source: {
+    index: "kibana_sample_data_flights",
+    query: {
+      bool: {
+        filter: [
+          {
+            term: {
+              Cancelled: false,
+            },
+          },
+        ],
+      },
+    },
+  },
+  dest: {
+    index: "sample_flight_delays_by_carrier",
+  },
+  pivot: {
+    group_by: {
+      carrier: {
+        terms: {
+          field: "Carrier",
+        },
+      },
+    },
+    aggregations: {
+      flights_count: {
+        value_count: {
+          field: "FlightNum",
+        },
+      },
+      delay_mins_total: {
+        sum: {
+          field: "FlightDelayMin",
+        },
+      },
+      flight_mins_total: {
+        sum: {
+          field: "FlightTimeMin",
+        },
+      },
+      delay_time_percentage: {
+        bucket_script: {
+          buckets_path: {
+            delay_time: "delay_mins_total.value",
+            flight_time: "flight_mins_total.value",
+          },
+          script: "(params.delay_time / params.flight_time) * 100",
+        },
+      },
+    },
+  },
+});
+console.log(response);
+----