Comments on chapter 13, version B 3.0

@seanmor5

One advice: build the phoenix from scratch, do not use the version from the example code.
If you use the wrong version of phoenix you get all kind of errors.
I used 1.7.11.

@sabiwara found all errors, see his post.

There is only one little thing. /priv/repo/seeds.exs need a minor correction.
author and title need to be switched

path = "priv/repo/booksummaries/booksummaries.txt"
df = Explorer.DataFrame.from_csv!(path, delimiter: "\t", header: false)
df = df[["column_3", "column_4", "column_7"]]
df = Explorer.DataFrame.rename(df, ["title", "author", "description"])
df
|> Explorer.DataFrame.to_rows()
|> Enum.each(&BookSearch.Library.create_book/1)