Declare rustls-pemfile to be unmaintained

Author: djc

crates/rustls-pemfile/RUSTSEC-0000-0000.md

@@ -0,0 +1,23 @@
+```toml
+[advisory]
+id = "RUSTSEC-0000-0000"
+package = "rustls-pemfile"
+date = "2025-11-28"
+url = "https://github.com/rustls/pemfile/issues/61"
+informational = "unmaintained"
+
+[versions]
+affected = [">= 0.1.0"]
+```
+
+# rustls-pemfile is unmaintained
+
+The rustls-pemfile crate is no longer maintained. The repository has been archived since August
+2025, and users are encouraged to depend directly on the underlying PEM parsing code included
+in rustls-pki-types since 1.9.0. The latest version of rustls-pemfile is in fact a thin wrapper
+around the same code used in rustls-pki-types, so migrating should be straightforward.
+
+The new API is represented by the [`PemObject`][PemObject] trait, which provides methods for
+reading a single or multiple PEM objects from a file or byte slice.
+
+[PemObject]: https://docs.rs/rustls-pki-types/1.12.0/rustls_pki_types/pem/trait.PemObject.html