Add an explanation to the deprecation of rhino_ast Node#children method.
Add an explanation to the deprecation of rhino_ast Node#children method.

PiperOrigin-RevId: 400737933

google/closure-compiler,monetate/closure-compiler,nawawi/closure-compiler,monetate/closure-compiler,ChadKillingsworth/closure-compiler,nawawi/closure-compiler,nawawi/closure-compiler,ChadKillingsworth/closure-compiler,google/closure-compiler,monetate/closure-compiler,monetate/closure-compiler,nawawi/closure-compiler,ChadKillingsworth/closure-compiler,google/closure-compiler,google/closure-compiler,ChadKillingsworth/closure-compiler