Keep prev/next links side by side on all screen widths

[Almaz]

In VPDocFooter.vue, the .prev-next links stack vertically on narrower screens,
which looks unnecessarily bulky.

Suggestion: remove the media query so the two-column layout applies at all widths:

.prev-next {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  grid-column-gap: 16px;
}