Update documentation to include PartialCallableObjectProxy

blog/05-decorators-which-accept-arguments.md

@@ -148,7 +148,7 @@ the above recipe to:
 ```python
 def optional_arguments(wrapped=None, arg=1):
     if wrapped is None:
-        return functools.partial(optional_arguments, arg=arg)
+        return PartialCallableObjectProxy(optional_arguments, arg=arg)
 
     @decorator
     def _wrapper(wrapped, instance, args, kwargs):
@@ -185,7 +185,7 @@ only argument syntax.
 ```python
 def optional_arguments(wrapped=None, *, arg=1):
     if wrapped is None:
-        return functools.partial(optional_arguments, arg=arg)
+        return PartialCallableObjectProxy(optional_arguments, arg=arg)
 
     @decorator
     def _wrapper(wrapped, instance, args, kwargs):
@@ -199,6 +199,12 @@ decorator argument as the positional argument for wrapped. For consistency,
 keyword only arguments can also be enforced for required arguments even
 though it isn't strictly necessary.
 
+The `PartialCallableObjectProxy` object is an implementation of
+`functools.partial()` which uses wrapt and preserves introspection for the
+wrapped callable object. This means you'll get better introspection
+capabilities when examining the decorated object in a code editor, which can
+be particularly useful.
+
 ```python
 def required_arguments(*, arg):
     @decorator