docs: update playground url (#50)

Author: Himenon

.github/ISSUE_TEMPLATE/BUG_REPORT.md

@@ -16,7 +16,7 @@ labels: "Status: Unconfirmed"
 <!--
   Write the minimum OpenAPI JSON or YAML Schema needed to reproduce the bug.
   If you can reproduce it with the following Playground, please post the URL too.
-  https://openapi-typescript-playground.netlify.app
+  https://openapi-typescript-code-generator-playground.netlify.app
 -->
 
 ## The current behavior

README.md

@@ -8,7 +8,7 @@ Since the parameters extracted from OpenAPI can be used freely, it can be used f
 
 ## Playground
 
-- [Playground](https://openapi-typescript-playground.netlify.app)
+- [Playground](https://openapi-typescript-code-generator-playground.netlify.app)
 
 ## Installation
 

docs/ja/README-ja.md

@@ -6,7 +6,7 @@ OpenAPI から抽出したパラメーターは自由に使うことができる
 
 ## Playground
 
-- [Playground](https://openapi-typescript-playground.netlify.app)
+- [Playground](https://openapi-typescript-code-generator-playground.netlify.app)
 
 ## DEMO