Jessica Parsons 92c1c0e002
Update widget docs (#876)
* Completed widget reference

* Rename extending.md to custom-widgets.md

* Move validation content into widget docs

* Add redirects for updated page titles

* Add note about yaml format options

* Add `field` option for `list`

* Add hidden widget

* Bold names of widget characteristics
2017-12-06 18:01:45 -08:00
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2017-12-06 18:01:45 -08:00
2017-12-06 18:01:45 -08:00