Write docs for project API module

src/ifcopenshell-python/ifcopenshell/api/project/create_file.py

@@ -38,6 +38,17 @@ class Usecase:
         :type version: str, optional
         :return: The created IFC file object.
         :rtype: ifcopenshell.file.file
+
+        Example::
+
+            # Start a new model.
+            model = ifcopenshell.api.run("project.create_file")
+
+            # It's currently a blank model, so typically the first thing we do
+            # is create a project in it.
+            project = ifcopenshell.api.run("root.create_entity", model, ifc_class="IfcProject", name="Test")
+
+            # ... and off we go!
         """
         self.settings = {"version": version}