Do not append suffix to text prompt

Do not append suffix to text prompt unless
there are choices or a default value specified.

Closes #413

test/Spectre.Console.Tests/Utilities/GitHubIssueAttribute.cs

@@ -0,0 +1,18 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Spectre.Console.Tests
+{
+    public sealed class GitHubIssueAttribute : Attribute
+    {
+        public int IssueId { get; }
+
+        public GitHubIssueAttribute(int issueId)
+        {
+            IssueId = issueId;
+        }
+    }
+}