Fix placeholder formatting interfering with build

Author: RebeccaTamachiro

src/content/docs/cloudflare-for-platforms/cloudflare-for-saas/security/certificate-management/enforce-mtls.mdx

@@ -338,8 +338,8 @@ In the API documentation, refer to [SSL properties of a custom hostname](/api/re
 		ssl: {
 			method: "http",
 			type: "dv",
-      custom_certificate: <certificate_string>,
-      custom_key: <certificate_private_key>,
+      custom_certificate: "<CERTIFICATE_STRING>",
+			custom_key: "<CERTIFICATE_PRIVATE_KEY>",
 			settings: {
 				"ciphers": ["ECDHE-ECDSA-AES128-GCM-SHA256","ECDHE-RSA-AES128-GCM-SHA256"],
 				"min_tls_version": "1.2"