Required Knowledge was a section of the page Getting Started previously. That made it awkward to link to, and didn't do one of the most-linked-to parts of our Wiki justice. I moved the section's contents into a page of its own, and linked it as the second item after the Introduction.
The old location still carries a link to the new page, so all old references should remain valid.
"Required Knowledge" made into own page
"Required Knowledge" made into own page
Every good solution is obvious once you've found it.