update readme

Author: bluebill1049

README.md

@@ -28,10 +28,31 @@ Check out this <a href="https://codesandbox.io/s/react-hook-form-hookforminput-r
 ## Quickstart
 
 ```jsx
+import React from 'react';
+import useForm from 'react-hook-form';
+import { RHFError } from 'react-hook-form-error';
+
+function App() {
+  const { handleSubmit, register, errors } = useForm();
+
+  return (
+    <form onSubmit={handleSubmit(data => console.log(data))}>
+      <input name="test" ref={register} />
+      <RHFError name="test" errors={errors} />
+      <button>submit</button>
+    </form>
+  );
+}
 ```
 
 ## API
-                                                                                                             |
+
+| Prop       | Type      | Required | Default | Description                                                                                                                                                     |
+| :--------- | :-------- | :------: | :-----: | :-------------------------------------------------------------------------------------------------------------------------------------------------------------- |
+| `name`     | string    |    ✓     |         | Unique name to register the custom input                                                                                                                        |
+| `errors`   | Object    |    ✓     |         | (optional when using <a href="https://react-hook-form.com/api#errors">errors</a>) React Hook Form <a href="https://react-hook-form.com/api#setValue">errors</a> |
+| `as`       | Component |          |         | Component reference eg: `Select` from `react-select`                                                                                                            |
+| `messages` | Object    |          |         | keys of error type's message                                                                                                                                    |
 
 ## Contributors
 

src/index.tsx

@@ -1,10 +1,11 @@
 import * as React from 'react';
+import { useFormContext } from 'react-hook-form';
 
 type ErrorFields = Record<string, { message?: string; type: string }>;
 
 const RHFError = <Errors extends ErrorFields, Name extends keyof Errors>({
   as,
-  errors,
+  errors: errorsFromProps,
   name,
   messages = {},
 }: {
@@ -13,6 +14,8 @@ const RHFError = <Errors extends ErrorFields, Name extends keyof Errors>({
   name: Name;
   messages?: Record<string, string>;
 }) => {
+  const methods = useFormContext();
+  const errors = errorsFromProps || methods.errors;
   const message = errors[name].message || messages[errors[name].type];
 
   if (!message) {