remove warning about default external qr code provider in README.md

In version 3.0, the qrcode provider must be explicitely set, so the
warning is not needed anymore.
Also rewrite the part about the curl library for php.

Author: NicolasCARPi

README.md

@@ -8,23 +8,16 @@ PHP library for [two-factor (or multi-factor) authentication](http://en.wikipedi
 <img src="https://raw.githubusercontent.com/RobThree/TwoFactorAuth/master/multifactorauthforeveryone.png">
 </p>
 
-## Warning:
-
-By default, this package uses the `lib/Providers/QRServerProvider.php` as QR code generator. This provider is __not__ suggested for applications where absolute security is needed, because it uses an external service for the QR code generation.
-
-
-You can make use of the included [Endroid](https://robthree.github.io/TwoFactorAuth/qr-codes/endroid.html) or [Bacon](https://robthree.github.io/TwoFactorAuth/qr-codes/bacon.html) providers which generate locally.
-
 ## Requirements
 
 * Requires PHP version >=8.2
-* [cURL](http://php.net/manual/en/book.curl.php) when using the provided `QRServerProvider` (default), `ImageChartsQRCodeProvider` or `QRicketProvider` but you can also provide your own QR-code provider.
 
 Optionally, you may need:
 
 * [sockets](https://www.php.net/manual/en/book.sockets.php) if you are using `NTPTimeProvider`
 * [endroid/qr-code](https://github.com/endroid/qr-code) if using `EndroidQrCodeProvider` or `EndroidQrCodeWithLogoProvider`.
 * [bacon/bacon-qr-code](https://github.com/Bacon/BaconQrCode) if using `BaconQrCodeProvider`.
+* [php-curl library](http://php.net/manual/en/book.curl.php) when using an external QR Code provider such as `QRServerProvider`, `ImageChartsQRCodeProvider`, `QRicketProvider` or any other custom provider connecting to an external service.
 
 ## Installation