Surface methods should be replaced by new core methods in the reference

Processing 4 added new core functions to replace the surface methods as can be seen in the Beta 5 and Beta 7 release notes. These changes are also mentioned here https://github.com/processing/processing4/issues/53

The reference needs to be updated to reflect those updates:

• windowResize(w, h) replaces surface.setSize(w, h)
• windowResizable() replaces surface.setResizable() (reference)
• windowMove(x, y) replaces surface.setLocation(x, y) (reference)
• windowTitle() replaces surface.setTitle() (reference)
• new windowResized() event handler
• new windowMoved() event handler

In case you want to contribute to this task, here is how to edit the reference.

Note: surface methods are still backwards compatible but you are encouraged to use the new methods for future sketches

Comienza con docs/reference.md y las páginas de referencia enlazadas para setResizable, setLocation y setTitle. Actualiza la referencia para describir los seis métodos de ventana y manejadores de eventos indicados; después, verifica que se cubra cada elemento de la lista de comprobación y que los métodos legacy de surface estén identificados como compatibles con versiones anteriores.