Fix HttpRequest::peer_addr documentation

Author: silverpill

actix-web/src/request.rs

@@ -264,7 +264,7 @@ impl HttpRequest {
     ///
     /// For expanded client connection information, use [`connection_info`] instead.
     ///
-    /// Will only return None when called in unit tests unless [`TestRequest::peer_addr`] is used.
+    /// Will return None when server listens on UDS socket or when called in unit tests unless [`TestRequest::peer_addr`] is used.
     ///
     /// [`TestRequest::peer_addr`]: crate::test::TestRequest::peer_addr
     /// [`connection_info`]: Self::connection_info