Updated Symfony code example (#249)

Example was using wrong notation, looks like a mix of array / named arguments. Updated to named arguments.

guides/Symfony.rst

@@ -47,9 +47,9 @@ stored in an AWS S3 bucket by key:
             // this is needed to prevent issues with truncated zip files
             //initialise zipstream with output zip filename and options.
             $zip = new ZipStream\ZipStream(
-                'outputName' => 'test.zip',
-                'defaultEnableZeroHeader' => true,
-                'contentType' => 'application/octet-stream',
+                outputName: 'test.zip',
+                defaultEnableZeroHeader: true,
+                contentType: 'application/octet-stream',
             );
 
             //loop keys - useful for multiple files
@@ -127,4 +127,4 @@ You need to add correct permissions
         's3' => ['ACL' => 'public-read'],
     ]);
 
-    fopen($path, 'w', null, $outputContext);
+    fopen($path, 'w', null, $outputContext);