Fix JSON formatting and clean up PHP code snippet

Author: OskarStark

README.md

@@ -53,8 +53,8 @@ composer require mcp/sdk
 
 Since this package has no tagged releases yet, it is required to extend your `composer.json`:
 ```json
-    "minimum-stability": "dev",
-    "prefer-stable": true,
+"minimum-stability": "dev",
+"prefer-stable": true
 ```
 
 ## ⚡ Quick Start: Stdio Server with Discovery
@@ -66,8 +66,6 @@ This example demonstrates the most common usage pattern - a `stdio` server using
 Create `src/CalculatorElements.php`:
 
 ```php
-<?php
-
 namespace App;
 
 use PhpMcp\Server\Attributes\McpTool;