Error : Unknown target name: "finegan2007". in the website (chapter 1 - Language Processing with python)

[PunithKumara0806]

[ekaf]

Close as fixed by #270.

The merged changes repair the make book build path that issue #258 was about, including the missing HTML dependency handling and the PDF-side build fixes needed to get the book targets working again. In particular, the fix covered the book.html / bibliography.html dependency and the LaTeX-side changes required to build successfully with xelatex.