Add missing documentation, and pull indentation in by one.

src/Generator.Bind/Structures/FlowDirection.cs

@@ -31,8 +31,19 @@ namespace Bind.Structures
     /// </summary>
     public enum FlowDirection
     {
+        /// <summary>
+        /// No defined flow.
+        /// </summary>
         Undefined = 0,
+
+        /// <summary>
+        /// Input parameter.
+        /// </summary>
         In,
+
+        /// <summary>
+        /// Output parameter, typically decorated with the out keyword.
+        /// </summary>
         Out
     }
 }