"Contribute to GitLab" in Help dropdown menu links to an incorrect URL on about.gitlab.com

Summary

The "Contribute to GitLab" link in the Help dropdown menu in GitLab CE links to an incorrect URL (or possibly an outdated URL).

Steps to reproduce

1. Open the "Help" dropdown menu in the navbar
2. Click "Contribute to GitLab"

Example Project

Any page on GitLab.com demonstrates this problem.

What is the current bug behavior?

A new browser tab is opened and directed to https://about.gitlab.com/contributing (without the trailing slash), which returns a 404 error page from about.gitlab.com.

What is the expected correct behavior?

The browser should be directed to https://about.gitlab.com/contributing/ (with the trailing slash), which is a valid URL, and is the same URL listed in the footer on https://about.gitlab.com/.

Relevant logs and/or screenshots

Output of checks

This bug happens on GitLab.com

Possible fixes

I think this is a one-character fix at https://gitlab.com/gitlab-org/gitlab-ce/blob/master/app/views/shared/_user_dropdown_contributing_link.html.haml#L2