dhelp binary package in Ubuntu Xenial amd64

 Read all documentation with a WWW browser. dhelp builds an index of
 all installed HTML documentation. You don't need a WWW server to read
 the documentation. dhelp offers a very fast search in the HTML documents.
 .
 You can access the online help system with the dhelp program or with
 your browser. The URL to point your browser at is (if you have a WWW
 server installed) http://localhost/doc/HTML/index.html , else (if you
 do not) file://localhost/usr/share/doc/HTML/index.html.

Source package