Add ability to add description to pull payment (#3363)

* Add ability to add description to pull payment

close #2625

* Add API support

* Remove 'Model.Description != "<br>"'

BTCPayServer/Models/WalletViewModels/PullPaymentsModel.cs

@@ -35,6 +35,7 @@ namespace BTCPayServer.Models.WalletViewModels
     {
         [MaxLength(30)]
         public string Name { get; set; }
+        public string Description { get; set; }
         [Required]
         public decimal Amount
         {