Suggestion: Add a "mify objects" example to tutorial Chapter 5

[psschwei]

As I was working my way through Chapter 5, one of the main questions I had was how to work with external dependencies. I found that info in one of the examples (

mellea/docs/examples/mify/mify.py

Lines 21 to 49 in 7013b04

	# You can also mify objects ad hoc.
	class MyStoreClass:
	def __init__(self, purchases: list[str]) -> None:
	self.purchases: list[str]
	store = MyStoreClass(["Beans", "Soil", "Watering Can"])
	mify(store)
	assert isinstance(store, MifiedProtocol)
	# Now, you can use these objects in MelleaSessions.
	store.format_for_llm()
	m = start_session()
	m.act(store)
	# However, unless your object/class has a __str__ function,
	# this won't do much good by itself. You need to specify how
	# mellea should process these objects as text. You can do this by
	# parameterizing mify.
	@mify(stringify_func=lambda x: f"Chain Location: {x.location}") # type: ignore
	class MyChain:
	def __init__(self, location: str):
	self.location = location
	# M operations will now utilize that string representation of the
	# object when interacting with it.
	m.query(MyChain("Northeast"), "Where is my chain located?")

), but it could be helpful to include in the tutorial as well.