Incorrect namespace usage fix

Incorrect name was applied, this fix is to resolve that issue for the GoogleMaps fragment.

Additionally: 
Updated comment to reflect that some users may include GoogleMaps as a node package and not an inline script include. 

Thus the 'script-src' directive needs to be updated to include 'https://maps.google.com` URI to allow for Googles CSP validation test ( 'https://maps.googleapis.com/maps/api/mapsjs/gen_204?csp_test=true'), this is called before GoogleMaps will actually load.

src/Fragments/GoogleMaps.php

@@ -1,14 +1,15 @@
 <?php
 
-namespace App\ContentSecurity\Fragments;
+namespace Silverstripe\CSP\Fragments;
 
 use Silverstripe\CSP\Directive;
-use Silverstripe\CSP\Fragments\Fragment;
 use Silverstripe\CSP\Policies\Policy;
 
 /*
  * Allows execution of Google Maps API related resources
- * Nonce on the https://maps.google.com/maps/api/js URL is required before using this fragment.
+ * Depending on how you include GoogleMaps API you will need either:
+ *  - inline script: requires nonce.
+ *  - node package in build-chain via dynamic calls: whitelist 'https://maps.google.com' via 'script-src' directive.
  *
  * https://content-security-policy.com/examples/google-maps/
  */