Chapter 3, Figure 3.1 references different markup removal

[pjhinton]

In the subsectionsection titled "The NLP Pipeline", the text says that Figure 3.1 summarizes material covered earlier in Chapter 3. The code annotating the step from HTML to ASCII references the nltk.clean_html() method. The preceding text uses BeautifulSoup.get_text() instead. This may confuse the reader.