CHANGELOG entry for PR:3378 (#3747)

Adds an entry to CHANGELOG.next.toml for the
[PR:3378](#3378)

---------

Co-authored-by: Fahad Zubair <fahadzub@amazon.com>
Co-authored-by: david-perez <d@vidp.dev>

Author: 3 people

CHANGELOG.next.toml

@@ -28,3 +28,17 @@ message = "Fix bug where stalled stream protection would panic with an underflow
 references = ["smithy-rs#3744"]
 meta = { "breaking" = false, "tada" = false, "bug" = true, "target" = "client" }
 author = "Velfi"
+
+[[smithy-rs]]
+message = """
+`FromParts<Protocol>::Rejection` must implement `std::fmt::Display`.
+
+Handlers can accept user-defined types if they implement 
+[FromParts<Protocol>](https://docs.rs/aws-smithy-http-server/latest/aws_smithy_http_server/request/trait.FromParts.html) with a `Rejection` 
+type that implements `std::fmt::Display` (preferably `std::error::Error`) to enable error logging when parameter construction from request parts fails.
+
+See the [changelog discussion for futher details](https://github.com/smithy-lang/smithy-rs/discussions/3749).
+"""
+references = ["smithy-rs#3746"]
+meta = { "breaking" = true, "tada" = false, "bug" = false, "target" = "server" }
+author = "drganjoo"