Add a Section Providing an Advanced Exercise in Scraping with Requests and BeautifulSoup

[runderwood]

Provide a more in-depth example of scraping with Python and these packages, using the same dataset to different ends.

[runderwood]

As discussed in the Etherpad, this portion should include two sections, each around scraping exercises using the same tools and dataset as the previous episode (see #11).

1. Scrape the UN site for the necessary data to count the number of Security Council resolutions per year and print these.
2. Generate and store CSV data, one row for each resolution, including year, resolution #, description, and a link to its text in PDF.