Remove the {{link}} macro

[MrBrain295]

The {{link}} macro isn't necessary or widely used it needs to be removed.

[teoli2003]

Yes, it should be removed. We have 3 left on mdn/content.

I think this is a remnant of the Wikimedia era.

Edit:
@yin1999 removed the last occurrence on MDN: mdn/content#19447
@MrBrain295 marked them as deprecated in mdn/yari#6865