Remove note about std/no-std scorer serialization compat

In 81389de we removed a note about
mixing the `std` and `no-std` feature when de/serializing
`ProbabilisticScorer`s but forgot to note that there was a second
copy of that note in the module documentation.

This removes that note.

Author: TheBlueMatt

lightning/src/routing/scoring.rs

@@ -49,11 +49,6 @@
 //! # }
 //! ```
 //!
-//! # Note
-//!
-//! Persisting when built with feature `no-std` and restoring without it, or vice versa, uses
-//! different types and thus is undefined.
-//!
 //! [`find_route`]: crate::routing::router::find_route
 
 use crate::ln::msgs::DecodeError;