docs: document support for standard forwarded proxy header by alan-agius4 · Pull Request #69418 · angular/angular

Update the security guide to document that the Angular SSR request handling pipeline now supports and validates the standard RFC 7239 `Forwarded` header.

Previously, only non-standard `X-Forwarded-*` headers were supported for resolving proxy-forwarded protocols, hosts, and ports. With this update:
- The standard `Forwarded` header parameters (such as `host` and `proto`) are validated and take precedence over corresponding `X-Forwarded-*` headers when trusted.
- The `trustProxyHeaders` option and `NG_TRUST_PROXY_HEADERS` environment variable can be configured to trust the `Forwarded` header.

For more details on the implementation, see the corresponding PR:
angular/angular-cli#33406