fix: add initial value prop and type definition

Closes: #25

Author: Marco Cesarato

src/InputSpinner.js

@@ -1048,6 +1048,7 @@ InputSpinner.propTypes = {
 	min: PropTypes.oneOfType([PropTypes.string, PropTypes.number]),
 	max: PropTypes.oneOfType([PropTypes.string, PropTypes.number]),
 	value: PropTypes.oneOfType([PropTypes.string, PropTypes.number]),
+	initialValue: PropTypes.oneOfType([PropTypes.string, PropTypes.number]),
 	step: PropTypes.oneOfType([PropTypes.string, PropTypes.number]),
 	precision: PropTypes.number,
 	rounded: PropTypes.bool,

src/index.d.ts

@@ -1,11 +1,12 @@
-import {Component} from "react";
+import React, {Component} from "react";
 import {StyleProp, ViewStyle} from "react-native";
 
 export interface ReactNativeInputSpinnerProps {
 	type?: string;
 	min?: string | number;
 	max?: string | number;
 	value?: string | number;
+	initialValue?: string | number;
 	step?: string | number;
 	precision?: number;
 	rounded?: boolean;