Make code examples in README.rst PEP8

Before:

```
$ flake8 one.py
one.py:3:1: E302 expected 2 blank lines, found 1
$ flake8 two.py
two.py:3:1: E302 expected 2 blank lines, found 1
```

After:

```
$ flake8 one.py
$ flake8 two.py
```