Fix ambiguous reference to "previous" section
This section originally came just after "10 minutes to pandas",
but now it's after the "Getting started tutorials".
Also, the examples have diverged a bit, so let's not pretend
that we are creating the same objects.

- [ ] closes #xxxx
- [ ] tests added / passed
- [ ] passes `black pandas`
- [ ] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

thanks @oefe 