Add validation notes to DAT types

SabreTools.DatFiles/Formats/Hashfile.cs

@@ -13,6 +13,9 @@ namespace SabreTools.DatFiles.Formats
     /// <summary>
     /// Represents parsing and writing of a hashfile such as an SFV, MD5, or SHA-1 file
     /// </summary>
+    /// <remarks>
+    /// TODO: Check and enforce required fields in output
+    /// </remarks>
     internal class Hashfile : DatFile
     {
         // Private instance variables specific to Hashfile DATs