Make syntax highlighting explicit in docs

src/ifcopenshell-python/ifcopenshell/api/void/add_filling.py

@@ -36,7 +36,9 @@ class Usecase:
         :return: The new IfcRelFillsElement relationship
         :rtype: ifcopenshell.entity_instance.entity_instance
 
-        Example::
+        Example:
+
+        .. code:: python
 
             # A bit of preparation, let's create some geometric contexts since
             # we want to create some geometry for our wall and opening.

src/ifcopenshell-python/ifcopenshell/api/void/add_opening.py

@@ -54,7 +54,9 @@ class Usecase:
         :return: The new IfcRelVoidsElement relationship
         :rtype: ifcopenshell.entity_instance.entity_instance
 
-        Example::
+        Example:
+
+        .. code:: python
 
             # A bit of preparation, let's create some geometric contexts since
             # we want to create some geometry for our wall and opening.

src/ifcopenshell-python/ifcopenshell/api/void/remove_filling.py

@@ -30,7 +30,9 @@ class Usecase:
         :return: None
         :rtype: None
 
-        Example::
+        Example:
+
+        .. code:: python
 
             # Create a wall
             wall = ifcopenshell.api.run("root.create_entity", model, ifc_class="IfcWall")

src/ifcopenshell-python/ifcopenshell/api/void/remove_opening.py

@@ -32,7 +32,9 @@ class Usecase:
         :return: None
         :rtype: None
 
-        Example::
+        Example:
+
+        .. code:: python
 
             # Create an oprhaned opening. Note that an orphaned opening is
             # invalid, as an opening can only exist when voiding another