Add docs to layer API

src/ifcopenshell-python/ifcopenshell/api/layer/add_layer.py

@@ -18,11 +18,32 @@
 
 
 class Usecase:
-    def __init__(self, file, **settings):
+    def __init__(self, file, Name=None):
+        """Adds a new layer
+
+        An IFC layer is like a CAD layer. Portions of an object's geometry
+        (typically portions of its 2D linework) can be assigned to layers, which
+        can provide stylistic information such as line weights, colours, or
+        simply be used for filtering.
+
+        Layers have historically been used to organise CAD data and included in
+        ISO standards such as ISO 13567 or by the AIA. This alllows IFC data to
+        be compatible with older, 2D-oriented, layer-based workflows.
+
+        Some software that are still based on layers, such as Tekla or ArchiCAD
+        may also use this layer information for filtering.
+
+        :param Name: The name of the layer. Defaults to "Unnamed".
+        :type Name: str, optional
+        :return: The newly created IfcPresentationLayerAssignment element
+        :rtype: ifcopenshell.entity_instance.entity_instance
+
+        Example:
+
+            ifcopenshell.api.run("layer.add_layer", model, Name="AI-WALL-FULL-DIMS-N")
+        """
         self.file = file
-        self.settings = {}
-        for key, value in settings.items():
-            self.settings[key] = value
+        self.settings = {"Name": Name or "Unnamed"}
 
     def execute(self):
-        return self.file.create_entity("IfcPresentationLayerAssignment", **{"Name": "Unnamed"})
+        return self.file.create_entity("IfcPresentationLayerAssignment", Name=self.settings["Name"])