add icingaweb2::module::doc

[rgevaert]

Currently there is no in module way to enable the documentation module.

Expected Behavior

include ::icingaweb2::module::doc

should enable the doc module. Passing ensure=absent should disable it.

Current Behavior

You need to use ::icingaweb2::module.

Possible Solution

Wrapper around ::icingaweb2::module like icingaweb2::module::director and icingaweb2::module::montoring