Remove credits and license from books category and give them their own heading

[coool9]

It implied that they are books about licenses and credits

I have not filled the todo below because it is irrelevant to my proposed change.
(todo:please remove this todo and the sections you did not check below before you make your pull request.
If you are unsure, please check other PRs like this one: #207 (comment))

In this pull request

• I am adding a new book.
• I am adding a new category
• Removing a book

Adding new book

• The book I am adding is _ _ _ _
• I am adding this book to _ _ _ _ section.
• I have read this book _ _ times.
• I think this book deserves to be in this list because _ _ _ _

If you are adding more than 1 books duplicate this section

Add new category

• The category I am adding is _ _ _ _
• The reason why I think this category should be there is because _ _ _ _
• • I have added at least one book to this category

If you are adding more than 1 category duplicate this section

Remove a book

• The book I am removing is _ _ _ _
• I am removing this book from _ _ _ _ section.
• I have read this book _ _ times.
• I think this book should not be in this list because _ _ _ _

If you are removing more than 1 book duplicate this section.