Increase project description length from 250 chars to at least 500

Problem to solve

Project description field is limited to 250 characters. This isn't long enough to provide an informative description that lives outside of git repository.

We should increase the limit to at least 500 characters, ideally 1000.

https://git.dreamhost.com/dreamhost/ndnsecure/edit#js-general-project-settings

Intended users

Directly: project maintainers, GitLab admins

Indirectly: everyone - as they active consume the project description by READING it.