Remove credit card samples (#896)

* removed credit card payment samples
* update docs to reflect sample changes
* update readme to recommend braintree for direct card payments

sample/payments/RefundCapture.php

@@ -4,7 +4,7 @@
 // process a refund on a Captured transaction.
 // API used: /v1/payments/capture/{<captureID>}/refund
 /** @var Capture $capture */
-$capture = require 'AuthorizationCapture.php';
+
 
 use PayPal\Api\Capture;
 use PayPal\Api\Refund;
@@ -14,15 +14,22 @@ use PayPal\Api\RefundRequest;
 // Create a refund object indicating
 // refund amount and call the refund method
 
-$refundRequest = new RefundRequest();
-$refundRequest->setAmount($amt);
+// Replace $captureId with any static Id you might already have. 
+$captureId = "<your authorization id here>";
+
+
 
 try {
     // Create a new apiContext object so we send a new
     // PayPal-Request-Id (idempotency) header for this resource
     $apiContext = getApiContext($clientId, $clientSecret);
 
+    // ### Retrieve Capture details
+    $capture = Capture::get($captureId, $apiContext);
+
+    // ### Refund the Capture 
     $captureRefund = $capture->refundCapturedPayment($refundRequest, $apiContext);
+
 } catch (Exception $ex) {
     // NOTE: PLEASE DO NOT USE RESULTPRINTER CLASS IN YOUR ORIGINAL CODE. FOR SAMPLE ONLY
     ResultPrinter::printError("Refund Capture", "Capture", null, $refundRequest, $ex);