Remove playground. Didn't work since Xcode 12

Author: krzyzanowskim

CHANGELOG

@@ -2,6 +2,7 @@
 - Adds OCB Authenticated-Encryption Algorithm (RFC7253)
 - build-framework.sh output CryptoSwift.xcframework
 - Xcode 12.2 maintenance updates
+- Removed CryptoSwift.playground (couldn't make it work since Xcode 12 update)
 
 1.3.2
 - Swift 5.3 update (Xcode 12)

CryptoSwift.playground/Contents.swift

@@ -194,8 +194,6 @@ In the project, you'll find [single scheme](https://mxcl.dev/PromiseKit/news/201
 * [AES-GCM](#aes-gcm)
 * [Authenticated Encryption with Associated Data (AEAD)](#aead)
 
-also check [Playground](/CryptoSwift.playground/Contents.swift)
-
 ##### Basics
 
 ```swift
@@ -428,8 +426,6 @@ do {
 }
 ```
 
-See [Playground](/CryptoSwift.playground/Contents.swift) for sample code that work with stream.
-
 ###### AES Advanced usage
 ```swift
 let input: Array<UInt8> = [0,1,2,3,4,5,6,7,8,9]