Create X25519MLKEM768 entry for nginx (#20189)

* Update pqc-support.mdx

* Remove reference to nginx+BoringSSL

Author: nisbet-hubbard

src/content/docs/ssl/post-quantum-cryptography/pqc-support.mdx

@@ -24,6 +24,7 @@ The list below is for reference only. Responsibility for third-party software li
 - [BoringSSL](https://boringssl.googlesource.com/boringssl/)
 - [rustls 0.23.22+](https://crates.io/crates/rustls)
 - Default for [rpxy 0.9.4+](https://github.com/junkurihara/rust-rpxy)
+- [NGINX](https://github.com/nginx/nginx) compiled with OpenSSL 3.5+ ([instructions](https://github.com/nginx/nginx/issues/288))
 - [Open Quantum Safe](https://openquantumsafe.org/)
     - C library: liboqs 0.10.0+
     - OpenSSL provider: oqs-provider 0.7.0+