Add Go Playground links

Author: jarreds

README.md

@@ -74,6 +74,8 @@ func main() {
 }
 ```
 
+[Go Playground](https://go.dev/play/p/aPr9Xd9dwrw)
+
 ### Generator Example
 
 ```go
@@ -119,6 +121,8 @@ func main() {
 }
 ```
 
+[Go Playground](https://go.dev/play/p/VCv2Sp3ar9Z)
+
 ### Suspension Example
 
 ```go
@@ -161,6 +165,8 @@ func main() {
 }
 ```
 
+[Go Playground](https://go.dev/play/p/yVUQyJpD3Wz)
+
 ### Cancellation
 
 ```go
@@ -209,6 +215,8 @@ func main() {
 }
 ```
 
+[Go Playground](https://go.dev/play/p/31pZ8Atq8GG)
+
 ## Detailed Usage
 
 ### Coroutine Creation