Improved godoc for EnableFullDuplex, copied text from stdlib

modules/caddyhttp/server.go

@@ -82,9 +82,23 @@ type Server struct {
 	// HTTP request headers.
 	MaxHeaderBytes int `json:"max_header_bytes,omitempty"`
 
-	// Enable full-duplex communication for HTTP/1.1 requests.
+	// Enable full-duplex communication for HTTP/1 requests.
 	// Only has an effect if Caddy was built with Go 1.21 or later.
 	//
+	// For HTTP/1 requests, the Go HTTP server by default consumes any
+	// unread portion of the request body before beginning to write the
+	// response, preventing handlers from concurrently reading from the
+	// request and writing the response. Enabling this option disables
+	// this behavior and permits handlers to continue to read from the
+	// request while concurrently writing the response.
+	//
+	// For HTTP/2 requests, the Go HTTP server always permits concurrent
+	// reads and responses, so this option has no effect.
+	//
+	// Test thoroughly with your HTTP clients, as some older clients may
+	// not support full-duplex HTTP/1 which can cause them to deadlock.
+	// See https://github.com/golang/go/issues/57786 for more info.
+	//
 	// TODO: This is an EXPERIMENTAL feature. Subject to change or removal.
 	EnableFullDuplex bool `json:"enable_full_duplex,omitempty"`