Implement CLI functionality and enhance README instructions

checkaddy_app/__init__.py

@@ -1,3 +1,11 @@
-from .app import CheckAddyApp
+from __future__ import annotations
 
 __all__ = ["CheckAddyApp"]
+
+
+def __getattr__(name: str) -> object:
+    if name == "CheckAddyApp":
+        from .app import CheckAddyApp
+
+        return CheckAddyApp
+    raise AttributeError(f"module {__name__!r} has no attribute {name!r}")