Make rackedit tolerant when there's no GUI available

README.md

@@ -49,5 +49,16 @@ For example, the window title can be changed before the frame becomes visible:
 The standard File menu does not contain the Exit/Quit command, so closing one
 editor window does not imply exiting the application that opened it.
 
+## Headless environments
+
+Requiring `rackedit` does not initialize Racket's GUI subsystem. This means that
+`(require rackedit)` is safe in a headless Racket process, for example a server
+process without access to an X11 or Wayland display.
+
+The GUI implementation is loaded only when `rkdt` is actually called. Calling
+`rkdt` still requires a usable graphical environment. Programs that also support
+a terminal editor can therefore choose that editor before calling `rkdt`, without
+merely requiring `rackedit` causing GTK initialization.
+
 Full API documentation is included as Scribble documentation in
 `scrbl/rkdt.scrbl`.