fix example

index.bs

@@ -1660,7 +1660,7 @@ this algorithm returns normally if compilation is allowed, and throws a
   When a document's response contains the headers:
 ```http
 Reporting-Endpoints: hashes-endpoint="https://example.com/reports"
-Content-Security-Policy: report-hash; report-to hashes-endpoint
+Content-Security-Policy: script-src 'report-sha256'; report-to hashes-endpoint
 ```
   and the document loads the script "main.js", a report similar to the following one will be sent:
 ```http