/usr/share/devhelp/books/ is in vala-0.20-doc 0.20.1-2ubuntu5.
This file is owned by root:root, with mode 0o755.
..
/usr/share/devhelp/books/vala-0.20/
/usr/share/devhelp/books/vala-0.20/attributes.html
/usr/share/devhelp/books/vala-0.20/classes.html
/usr/share/devhelp/books/vala-0.20/default.css
/usr/share/devhelp/books/vala-0.20/delegates.html
/usr/share/devhelp/books/vala-0.20/enums.html
/usr/share/devhelp/books/vala-0.20/exceptions.html
/usr/share/devhelp/books/vala-0.20/expressions.html
/usr/share/devhelp/books/vala-0.20/index.html
/usr/share/devhelp/books/vala-0.20/interfaces.html
/usr/share/devhelp/books/vala-0.20/methods.html
/usr/share/devhelp/books/vala-0.20/namespaces.html
/usr/share/devhelp/books/vala-0.20/overview.html
/usr/share/devhelp/books/vala-0.20/statements.html
/usr/share/devhelp/books/vala-0.20/structs.html
/usr/share/devhelp/books/vala-0.20/types.html
/usr/share/devhelp/books/vala-0.20/vala-0.20.devhelp2