Update phet-software-design-patterns.md

Author: zepumph

doc/phet-software-design-patterns.md

@@ -83,9 +83,11 @@ Interested developers: JG, DB, CK
 A standard pattern described in https://en.wikipedia.org/wiki/Observer_pattern
 
 `Property`, `Emitter`, ... and their role in MVC
+NOTE: when this gets flushed out, scenery input system, options callbacks should be passed the SCENERY/Event from their input listeners.
 
 Very important pattern for new developers
 
+
 ## `options` and `config` Parameters
 
 TODO This section needs some work. The pattern is probably "configurtion" for parameterizing types, which we use to avoid an explosion of constructor parameters. `config` and `options` are the two implementation of that pattern that PhET typically uses.