Write documentation for structural API module

src/ifcopenshell-python/ifcopenshell/api/structural/add_structural_load.py

@@ -20,14 +20,32 @@ import ifcopenshell.api
 
 
 class Usecase:
-    def __init__(self, file, **settings):
+    def __init__(self, file, name=None, ifc_class="IfcStructuralLoadLinearForce"):
+        """Adds a new structural load
+
+        Structural loads may be actions or reactions. A simple load might be a
+        static and be linear, planar, or a single point. Alternatively, loads
+        may be defined as a configuration of multiple loads.
+
+        :param name: The name of the load
+        :type name: str,optional
+        :param ifc_class: The subtype of IfcStructuralLoad to create. Consult
+            the IFC documentation to see all the types of loads.
+        :type ifc_class: str
+        :return: The newly created load entity, depending on the ifc_class
+            specified.
+        :rtype: ifcopenshell.entity_instance.entity_instance
+
+        Example::
+
+            # Create a simple linear load
+            ifcopenshell.api.run("structural.add_structural_load", model)
+        """
         self.file = file
         self.settings = {
-            "name": None,
-            "ifc_class": "IfcStructuralLoadLinearForce",
+            "name": name,
+            "ifc_class": ifc_class,
         }
-        for key, value in settings.items():
-            self.settings[key] = value
 
     def execute(self):
         return self.file.create_entity(self.settings["ifc_class"], Name=self.settings["name"])