add xml comments for IUnboundSubscriptionDefinition.cs

dotnet/src/Microsoft.AutoGen/Contracts/PythonEquiv/IUnboundSubscriptionDefinition.cs

@@ -3,7 +3,16 @@
 
 namespace Microsoft.AutoGen.Contracts.Python;
 
+/// <summary>
+/// Defines a subscription that is not yet bound to a specific agent type.
+/// This interface allows the creation of dynamic subscriptions that can later be associated with an agent.
+/// </summary>
 public interface IUnboundSubscriptionDefinition
 {
+    /// <summary>
+    /// Binds the subscription to a specific agent type, creating a concrete <see cref="ISubscriptionDefinition"/>.
+    /// </summary>
+    /// <param name="agentType">The agent type to associate with the subscription.</param>
+    /// <returns>A new <see cref="ISubscriptionDefinition"/> bound to the specified agent type.</returns>
     public ISubscriptionDefinition Bind(AgentType agentType);
 }