On pages like Configuring Columns, you can see references to Design Guidelines:

The single left-most column will always be blue, representing items in 'new' state (as per our design guidelines).

The link currently points to developer.atlassian.com - but instead, it should point to https://atlassian.design/guidelines/product/components/lozenges or similar.

We should also check other links in the documentation to developer.atlassian.com to make sure there are no other broken links.