refactor: pool maxIdle description

Author: wellwelwel

typings/mysql/lib/Pool.d.ts

@@ -30,7 +30,7 @@ export interface PoolOptions extends ConnectionOptions {
   connectionLimit?: number;
 
   /**
-   * The minimum number of idle connections. (Default: 10)
+   * The maximum number of idle connections. (Default: same as `connectionLimit`)
    */
   maxIdle?: number;