Add nb_views on public docs

[virgile-dev]

Feature Request

Is your feature request related to a problem or unsupported use case? Please describe. Users who use Docs to create public documents or knowledge pages want to know how many times their page was viewed.

Describe the solution you'd like This information could be public or only shown to owner and admins. @rl-83 what do you think ? And should be displayed on the doc. Probably at the top. We should add this capability to subdoc as welll

Describe alternatives you've considered A clear and concise description of any alternative solutions or features you've considered.

Discovery, Documentation, Adoption, Migration Strategy If you can, explain how users will be able to use this and possibly write out some documentation (if applicable). Maybe add a screenshot or design?

Do you want to work on it through a Pull Request?