Merge pull request #1 from wyxxle/patch-1

variable fix

Author: dfreniche

docs/40-using-arrays/2-search-inside-objects-in-arrays.mdx

@@ -38,7 +38,7 @@ let nineNinetyNine = {$match: {"attributes.key": "msrp", "attributes.value": 9.9
 let showOnlyTheseFields = {$project: {_id: 0, title: 1, year: 1, totalInventory: 1, available: 1, "attributes": 1}};
 
 db.books.aggregate([
-    firstEditions,
+    nineNinetyNine,
     showOnlyTheseFields,
 ]);
 ```
@@ -51,4 +51,4 @@ db.books.aggregate([
     {$match: {"attributes.key": "msrp", "attributes.value": 9.99} },
    {$project: {title: 1, attributes: 1}}
 ]);
-```
+```