Feature request: Option to accept inherited docstrings

**Is this a BUG REPORT or FEATURE REQUEST?**:

* [ ] bug
* [x] feature

## Description of Bug or Feature

Many tools (e.g. `inspect.getdoc`, Sphinx) allow methods in subclasses to inherit the docstring of the parent method:
```python
class Foo:
def do_it(self):
"""
Do the thing!
"""
pass

class SpecialFoo(Foo):
def do_it(self):
print('So special!')
```
In these cases, I usually only add a separate docstring to `SpecialFoo.do_it` if its behavior differs significantly from what one would expected after reading the docstring of `Foo.do_it`. In most cases, the docstring of `Foo.do_it` is just fine.

Hence I'd like an option to not count these cases as missing.