feat(EnvelopeReceiverReadOnly): Created endpoint for ShowEnvelope view

EnvelopeGenerator.Extensions/EncodingExtensions.cs

@@ -10,6 +10,7 @@ namespace EnvelopeGenerator.Extensions
     {
         public static string EncodeEnvelopeReceiverId(this long readOnlyId)
         {
+            //The random number is used as a salt to increase security but it is not saved in the database.
             string combinedString = $"{Random.Shared.Next()}::{readOnlyId}::{Random.Shared.Next()}";
             byte[] bytes = Encoding.UTF8.GetBytes(combinedString);
             string base64String = Convert.ToBase64String(bytes);