* initial thoughts on default fields

* address some feedback

* more work on feedback

* work on alternatives section

* clean up later sections

* elaborate expectations

* address some feedback

* remove manual wrapping

* address some feedback

* rework and move default to alternatives

* work on intro para

* rework grammar

* speell chek

* fix a few syntax issues

* add examples for validity

* add example for private defaults

* address some feedback

* address some more feedback

* add ctor and builder example

* fix typo in grammar

* keep flow through examples

* clarify errors

* clarify default derive

* rename examples section

* add trailing comma

* replace doc comments with comments

* remove builder example

* work on some feedback

* add extra note on field privacy