Update doc link?

Problem/Motivation

I was looking for documentation, and found a link to the Drupal 7 Github README, which could be updated?

Steps to reproduce

Proposed resolution

1. Update the default branch to 4.x on GitLab (https://git.drupalcode.org/project/queue_unique)
2. Under "Resources", remove: https://github.com/e0ipso/unique_queue/blob/7.x-1.x/README.md
3. Under "Resources", add link: Documentation

Remaining tasks

User interface changes

API changes

Data model changes