docs: README.md 내 사용법 업데이트

Author: bumssooooo

README.md

@@ -5,19 +5,33 @@
 [![License](https://img.shields.io/cocoapods/l/RandomNumberTextField.svg?style=flat)](https://cocoapods.org/pods/RandomNumberTextField)
 [![Platform](https://img.shields.io/cocoapods/p/RandomNumberTextField.svg?style=flat)](https://cocoapods.org/pods/RandomNumberTextField)
 
-## Example
 
-To run the example project, clone the repo, and run `pod install` from the Example directory first.
+## 📸 Preview
+<img src="https://user-images.githubusercontent.com/73675540/198973316-f814734d-235d-44a4-a8e4-bc2f994e5b94.gif" width="40%" height="40%/"><br>
 
-## Requirements
+## 🏗 Installation
+* [CocoaPods](https://guides.cocoapods.org/using/using-cocoapods.html):
+```ruby
+pod 'RandomNumberTextField'
+```
 
-## Installation
+## 🐒 Usage
+* Storyboard  
+just subclassing!
+<br><img src="https://user-images.githubusercontent.com/73675540/198974933-b1c849b3-d37f-4743-9693-c901ca32ff61.png" width="60%" height="60%/"><br>
 
-RandomNumberTextField is available through [CocoaPods](https://cocoapods.org). To install
-it, simply add the following line to your Podfile:
+* Code-Base  
+just init!
+``` swift
+let randomKeyboard = RandomNumberTextField()
+```
 
-```ruby
-pod 'RandomNumberTextField'
+## 🎨 Custom
+you can change keyboard color and font
+``` swift
+func setKeyboardBackgroundColor(_ color: UIColor?)
+func setKeyboardFont(_ font: UIFont) 
+func setKeyboardTitleColor(_ color: UIColor?, for state: UIControl.State) 
 ```
 
 ## Author