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

Beginne mit docs/reference.md und den verknüpften Referenzseiten für setResizable, setLocation und setTitle. Aktualisiere die Referenz, um die sechs aufgeführten Fenstermethoden und Ereignishandler zu beschreiben, und überprüfe anschließend, dass jeder Punkt der Checkliste abgedeckt ist und die Legacy-Surface-Methoden als abwärtskompatibel gekennzeichnet sind.