docs(b-form-radio): add note that unchecked-value is not submitted via native form submit (closes #4089) (#4090)

tmorehouse · web-flow · commit c6a3030bba68 · 2019-09-13T15:54:50.000-03:00
diff --git a/src/components/form-checkbox/README.md b/src/components/form-checkbox/README.md
@@ -209,6 +209,12 @@ pre-selected.
 When placing individual `<b-form-checkbox>` components within a `<b-form-checkbox-group>`, most
 props and the `v-model` are inherited from the `<b-form-checkbox-group>`.
 
+**Note:** the `unchecked-value` prop _does not_ affect the native `<input>`'s `value` attribute,
+because browsers don't include unchecked boxes in form submissions. To guarantee that one of two
+values is submitted in a native `<form>` submit (e.g. `'yes'` or `'no'`), use radio inputs instead.
+This is the same limitation that
+[Vue has with native checkbox inputs](https://vuejs.org/v2/guide/forms.html#Checkbox-1).
+
 ### Multiple checkboxes and accessibility
 
 When binding multiple checkboxes together, you must set the `name` prop to the same value for all
