Copy some new links from serde.rs to the crate-level doc

Author: dtolnay

serde/src/lib.rs

@@ -53,6 +53,9 @@
 //!   *(deserialization only)*
 //! - [Envy Store], a way to deserialize [AWS Parameter Store] parameters into
 //!   Rust structs. *(deserialization only)*
+//! - [S-expressions], the textual representation of code and data used by the
+//!   Lisp language family.
+//! - [D-Bus]'s binary wire format.
 //!
 //! [JSON]: https://github.com/serde-rs/json
 //! [Bincode]: https://github.com/TyOverby/bincode
@@ -71,6 +74,8 @@
 //! [Envy Store]: https://github.com/softprops/envy-store
 //! [Cargo]: http://doc.crates.io/manifest.html
 //! [AWS Parameter Store]: https://docs.aws.amazon.com/systems-manager/latest/userguide/systems-manager-paramstore.html
+//! [S-expressions]: https://github.com/rotty/lexpr-rs
+//! [D-Bus]: https://docs.rs/zvariant
 
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