Add example referenced from Collection::bulkWrite()

examples/Collection-bulkWrite.php

+<?php
+require __DIR__ . "/" . "../vendor/autoload.php";
+
+function dumpWriteResults(MongoDB\WriteResult $result) {
+    printf("Inserted %d documents, upserted %d, updated %d and deleted %d\n",
+        $result->getInsertedCount(), $result->getUpsertedCount(),
+        $result->getModifiedCount(), $result->getDeletedCount()
+    );
+
+    if ($result->getUpsertedCount()) {
+        foreach ($result->getUpsertedIds() as $index => $id) {
+            printf("upsertedId[%d]: %s", $index, $id);
+        }
+    }
+}
+function dumpCollection($collection) {
+    printf("\n---\nDumping all documents in: %s.%s\n",
+        $collection->getDatabaseName(),
+        $collection->getCollectionName()
+    );
+    $n = 0;
+    foreach($collection->find() as $document) {
+        var_dump($document);
+        $n++;
+    }
+    printf("Found %d documents\n", $n);
+}
+
+
+$manager = new MongoDB\Manager("mongodb://localhost:27017");
+$collection = new MongoDB\Collection($manager, "crud.bulkWrite");
+$result = $collection->bulkWrite([
+    [
+        "insertOne" => [
+            [
+                "name" => "Hannes Magnusson",
+                "company" => "10gen",
+            ]
+        ],
+    ],
+    [
+        "insertOne" => [
+            [
+                "name" => "Jeremy Mikola",
+                "company" => "10gen",
+            ]
+        ],
+    ],
+    [
+        "updateMany" => [
+            ["company" => "10gen"],
+            ['$set' => ["company" => "MongoDB"]],
+        ],
+    ],
+    [
+        "updateOne" => [
+            ["name" => "Hannes Magnusson"],
+            ['$set' => ["viking" => true]],
+        ],
+    ],
+]);
+
+dumpWriteResults($result);
+dumpCollection($collection);
+
+
+$result = $collection->bulkWrite([
+    [
+        "deleteOne" => [
+            ["company" => "MongoDB"],
+        ],
+    ],
+    [
+        "updateOne" => [
+            ["name" => "Hannes Magnusson"],
+            ['$set' => ["nationality" => "Icelandic"]],
+            ["upsert" => true],
+        ],
+    ],
+    [
+        "deleteMany" => [
+            ["nationality" => [ '$ne' => "Icelandic"]],
+        ],
+    ],
+]);
+
+echo "\n\n";
+dumpWriteResults($result);
+dumpCollection($collection);
+
+$result = $collection->bulkWrite([
+    [
+        "deleteMany" => [
+            [],
+        ],
+    ],
+]);
+
+echo "\n\n";
+dumpWriteResults($result);
+dumpCollection($collection);
+