update legend title type

#266

Author: bvenn

src/Plotly.NET/Layout/ObjectAbstractions/Common/Legend.fs

@@ -27,7 +27,7 @@ type Legend() =
             [<Optional; DefaultParameterValue(null)>] ?Y: float,
             [<Optional; DefaultParameterValue(null)>] ?YAnchor: StyleParam.YAnchorPosition,
             [<Optional; DefaultParameterValue(null)>] ?VerticalAlign: StyleParam.VerticalAlign,
-            [<Optional; DefaultParameterValue(null)>] ?Title: string
+            [<Optional; DefaultParameterValue(null)>] ?Title: Title
         ) =
         Legend()
         |> Legend.style (
@@ -66,7 +66,7 @@ type Legend() =
             [<Optional; DefaultParameterValue(null)>] ?Y: float,
             [<Optional; DefaultParameterValue(null)>] ?YAnchor: StyleParam.YAnchorPosition,
             [<Optional; DefaultParameterValue(null)>] ?VerticalAlign: StyleParam.VerticalAlign,
-            [<Optional; DefaultParameterValue(null)>] ?Title: string
+            [<Optional; DefaultParameterValue(null)>] ?Title: Title
         ) =
         (fun (legend: Legend) ->
             BGColor |> DynObj.setValueOpt legend "bgcolor"
@@ -76,7 +76,7 @@ type Legend() =
             ItemWidth |> DynObj.setValueOpt legend "itemwidth"
             X |> DynObj.setValueOpt legend "x"
             Y |> DynObj.setValueOpt legend "y"
-            Title |> DynObj.setValueOpt legend "Title"
+            Title |> DynObj.setValueOpt legend "title"
 
             Orientation |> DynObj.setValueOptBy legend "orientation" StyleParam.Orientation.convert
             TraceOrder |> DynObj.setValueOptBy legend "traceorder" StyleParam.TraceOrder.convert