Missing Description attribute for payloadSpec members

[MicBoucinha]

This worked previously, at least on Generator v0.3.0.

The fix seems to be easy enough and should be handled here, I think:

generators/src/Device.tt

Lines 886 to 893 in 6d014c5

	/// <summary>
	/// <#= member.Value.Description #>
	/// </summary>
	public <#= memberType #> <#= member.Key #>;
	<#
	}
	#>

If needed, let me know and I can try to submit a PR