MD fixes 2

Author: rustagir

source/fundamentals/bson.txt

@@ -234,12 +234,11 @@ operation:
 
 .. code-block:: go
 
-   myCollection := client.Database("school").Collection("students")
+   coll := client.Database("school").Collection("students")
    filter := bson.D{{"age", 8}}
 
    var result bson.D
-   cursor := myCollection.FindOne(context.TODO(), filter)
-   err = cursor.Decode(&result)
+   err := coll.FindOne(context.TODO(), filter).Decode(&result)
    ...
 
    fmt.Println(result)