docs: improve document for setChecked(), setSelected() and setValue()

docs/api/wrapper/setChecked.md

@@ -1,9 +1,19 @@
-## setChecked(value)
+## setChecked(checked)
 
-Sets the value of a radio or checkbox `<input>`.
+Sets the value to an input element of type checkbox or an input element of type radio.
+
+When you try to set the value to state via `v-model` by `radioInput.element.checked = true; radioInput.trigger('input')`, `v-model` is not triggered. `v-model` is triggered by `change` event.
+
+`checkboxInput.setChecked(checked)` is an alias of the following code.
+
+```js
+checkboxInput.element.checked = checked
+checkboxInput.trigger('click')
+checkboxInput.trigger('change')
+```
 
 - **Arguments:**
-  - `{Boolean} selected`
+  - `{Boolean} checked (default: true)`
 
 - **Example:**
 

docs/api/wrapper/setSelected.md

@@ -1,9 +1,15 @@
-## setSelected(value)
+## setSelected()
 
-Sets a specified `<option>` as selected in a `<select>`.
+Selects a option element.
 
-- **Arguments:**
-  - `{Boolean} selected`
+When you try to set the value to state via `v-model` by `option.element.selected = true; parentSelect.trigger('input')`, `v-model` is not triggered. `v-model` is triggered by `change` event.
+
+`option.setchecked(checked)` is an alias of the following code.
+
+```js
+option.element.selected = true
+parentSelect.trigger('change')
+```
 
 - **Example:**
 
@@ -15,5 +21,4 @@ const wrapper = shallowMount(Foo)
 const options = wrapper.find('select').findAll('option')
 
 options.at(1).setSelected()
-expect(wrapper.text()).to.contain('option1')
 ```

docs/api/wrapper/setValue.md

@@ -1,6 +1,13 @@
 ## setValue(value)
 
-Sets the value of a text `<input>`.
+Sets the value to an input element of type text.
+
+`textInput.setValue(value)` is an alias of the following code.
+
+```js
+textInput.element.value = value
+textInput.trigger('input')
+```
 
 - **Arguments:**
   - `{String} value`