New tutorials: publish a package

[ddbeck]

(For more information about this issue, please see #194).

We need a short section to follow the section about making a package (see #203) (i.e., as its own file). It should satisfy the following goals:

• show how to register with PyPI/testPyPI
• ask the reader to install twine (by this point they should be pretty comfortable installing things!)
• demonstrate uploading an sdist and wheel with twine (initial version)
• demonstrate uploading an sdist and wheel with twine (second version)
• admire your handiwork on the web

Important note: aside from registration, have the reader use testPyPI to learn the steps in this section.

It's OK to assume that the reader completed the previous section successfully and has a package that they can use with testPyPI.

When opening pull requests for this issue, please submit to the develop branch. If you have questions that concern contributing more generally, please use issue #194. Otherwise, feel free to comment with questions or feedback. Thanks!

[souravsingh]

@ddbeck I will be working on this

[jeanas]

This has long existed (Packaging Python projects).