Ordering is not respected in sidebar menu

[johnbillion]

The sub pages of https://docs.altis-dxp.com/guides/upgrading/ all contain an order: header in their frontmatter, but this isn't being respected. The sub pages are listed in the sidebar menu in alphabetical order, which isn't desirable.

Screenshot

[mikelittle]

This could wait until after the new build system is in place, and server as an acceptance test.