Added throws for docblock (#52063)

Author: siarheipashkevich

src/Illuminate/Contracts/Cache/Lock.php

@@ -18,6 +18,8 @@ public function get($callback = null);
      * @param  int  $seconds
      * @param  callable|null  $callback
      * @return mixed
+     *
+     * @throws \Illuminate\Contracts\Cache\LockTimeoutException
      */
     public function block($seconds, $callback = null);