Server install doc - fix broken curl command
Allow menus to include hyperlinks

Menus were only allowed to link to other Jekyll-managed pages. This
allows hyperlinks to non-Jekyll-managed pages to be used. Currently, the
links must still be on the same site.
Nav submenus also include the top item

Previously, hovering over the 'documentation' nav item (as an example)
would reveal a pop-down menu. But it was not clear that the
'documentation' item itself had a page, meaning sometimes people would
miss the content. This adds the 'documentation' item itself to the
pop-down menu.
This closes #14.
This closes #15.