docs: discarded server TCP connection config (#1473)

The Server type accepts TCP configuration parameters (keepalive &
TCP_NODELAY) which are only respected when using serve() or
serve_with_shutdown().

Serve methods that take a stream of AsyncRead + AsyncWrite are
necessarily unaware of the underlying transport, and therefore silently
discard any TCP specific configuration.

Co-authored-by: Lucio Franco <luciofranco14@gmail.com>

tonic/src/transport/server/mod.rs

@@ -645,8 +645,10 @@ impl<L> Router<L> {
             .await
     }
 
-    /// Consume this [`Server`] creating a future that will execute the server on
-    /// the provided incoming stream of `AsyncRead + AsyncWrite`.
+    /// Consume this [`Server`] creating a future that will execute the server
+    /// on the provided incoming stream of `AsyncRead + AsyncWrite`.
+    ///
+    /// This method discards any provided [`Server`] TCP configuration.
     ///
     /// [`Server`]: struct.Server.html
     pub async fn serve_with_incoming<I, IO, IE, ResBody>(
@@ -674,11 +676,13 @@ impl<L> Router<L> {
             .await
     }
 
-    /// Consume this [`Server`] creating a future that will execute the server on
-    /// the provided incoming stream of `AsyncRead + AsyncWrite`. Similar to
+    /// Consume this [`Server`] creating a future that will execute the server
+    /// on the provided incoming stream of `AsyncRead + AsyncWrite`. Similar to
     /// `serve_with_shutdown` this method will also take a signal future to
     /// gracefully shutdown the server.
     ///
+    /// This method discards any provided [`Server`] TCP configuration.
+    ///
     /// [`Server`]: struct.Server.html
     pub async fn serve_with_incoming_shutdown<I, IO, IE, F, ResBody>(
         self,