PEP 698: reword the disadvantages section (#2894)

We claimed that there are two disadvantages to overrides:
it makes code more verbose, and requires developers to update
subclasses when possibly-breaking changes happen to base classes.

In discussion, it was pointed out that the second disadvantage is
kind of strange - it is exactly the same as the advantage of
using @override in the first place because the whole point is that
it is not usually safe to assume subclasses can be unchanged when
a method they override is removed from a base class.

I think just pointing out verbosity is good enough, I think it's
understood that more verbose code potentially requires more edits
to change, and in reality I think the case when it was safe to
ignore invalidated overrides is pretty rare so making that a big
focus seems a little weird.

pep-0698.rst

@@ -167,12 +167,7 @@ Providing support for ``@override`` in static checks would add value because
 Disadvantages
 -------------
 
-The two disadvantages we are aware of to using ``@override`` are that
-
-- The code becomes more verbose - overriding methods require one additional
-  line.
-- Adding or removing base class methods that impact overrides will require
-  updating subclass code.
+Using ``@override`` will make code more verbose.
 
 
 Specification