Disallow bare URLs from project
What does this MR do?
Bare Markdown URLs aren't automatically converted to clickable links in HTML.
This MR resolves instances of that in the project, and adds the appropriate Markdownlint rule to enforce it via the MD034 rule
Relates to: https://gitlab.com/gitlab-com/gitlab-docs/issues/287. Related to https://gitlab.com/charts/gitlab/issues/1529
Edited by Marcel Amirault