dosbox .hdd: missed couple places

Author: vadosnaprimer

src/BizHawk.Client.EmuHawk/MainForm.VSystem.cs

@@ -981,7 +981,7 @@ private void Ti83PaletteMenuItem_Click(object sender, EventArgs e)
 			if (result.IsOk()) AddOnScreenMessage("Palette settings saved");
 		}
 
-		private static readonly FilesystemFilterSet DOSBoxHDDImageFilterSet = new(new FilesystemFilter("DOSBox HDD Images", new[] { "bin" }))
+		private static readonly FilesystemFilterSet DOSBoxHDDImageFilterSet = new(new FilesystemFilter("DOSBox HDD Images", new[] { "hdd" }))
 		{
 			AppendAllFilesEntry = false,
 		};

src/BizHawk.Emulation.Cores/Computers/DOS/DOSBox.ISettable.cs

@@ -268,7 +268,7 @@ public class SyncSettings
 			public float MouseSensitivity { get; set; }
 
 			[DisplayName("Mount Formatted Hard Disk Drive")]
-			[Description("Determines whether to mount an empty writable formatted hard disk in drive C:. The hard disk will be fully located in memory so make sure you have enough RAM available. Its contents can be exported to the host filesystem.\n\nThis value will be ignored if a hard disk image (.bin) is provided.")]
+			[Description("Determines whether to mount an empty writable formatted hard disk in drive C:. The hard disk will be fully located in memory so make sure you have enough RAM available. Its contents can be exported to the host filesystem.\n\nThis value will be ignored if a hard disk image (.hdd) is provided.")]
 			[DefaultValue(HardDiskOptions.None)]
 			[TypeConverter(typeof(DescribableEnumConverter))]
 			public HardDiskOptions FormattedHardDisk { get; set; }