[SSL] Add Spectrum to Total TLS limitations (#20774)

Author: ngayerie

src/content/docs/ssl/edge-certificates/additional-options/total-tls/index.mdx

@@ -32,6 +32,7 @@ Total TLS does not issue certificates for any hostnames used with:
 
 * [Cloudflare Load Balancing](/load-balancing/)
 * [Cloudflare Tunnel](/cloudflare-one/connections/connect-networks/routing-to-tunnel/)
+* [Cloudflare Spectrum](/spectrum/)
 
 You can use other types of certificates or manually [order advanced certificates](/ssl/edge-certificates/advanced-certificate-manager/manage-certificates/#create-a-certificate) for these hostnames.