Update README.md

README.md

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 [![Build Status](https://travis-ci.org/yaslab/ULID.swift.svg?branch=master)](https://travis-ci.org/yaslab/ULID.swift)
 [![codecov](https://codecov.io/gh/yaslab/ULID.swift/branch/master/graph/badge.svg)](https://codecov.io/gh/yaslab/ULID.swift)
+
+Implementation of [ULID](https://github.com/ulid/spec/blob/master/README.md) in Swift.
+
+## Usage
+
+### Generate ULID
+
+```swift
+// Generate ULID using current time
+let ulid = ULID()
+
+// Get ULID string
+let string: String = ulid.ulidString
+// Get ULID binary data
+let data: Data = ulid.ulidData
+```
+
+### Parse ULID
+
+```swift
+// Parse ULID string
+let ulid = ULID(ulidString: "01D0YHEWR9WMPY4NNTPK1MR1TQ")
+
+// Get Timestamp as Date
+let timestamp: Date = ulid.timestamp
+```
+
+## Installation
+
+### CocoaPods
+
+```
+pod 'ULID.swift', '~> 1.0.0'
+```
+
+### Carthage
+
+```
+github "yaslab/ULID.swift" ~> 1.0.0
+```
+
+### Swift Package Manager
+
+```
+.package(url: "https://github.com/yaslab/ULID.swift.git", .upToNextMinor(from: "1.0.0"))
+```
+
+## License
+
+ULID.swift is released under the MIT license. See the [LICENSE](https://github.com/yaslab/ULID.swift/blob/master/LICENSE) file for more info.