Adding Wikivoyage to the default interwiki map

Note that this has already been added to the WMF interwiki map, so
it will have no effect on WMF wikis, only 3rd party wikis.

I'll update the link protocols in a follow-up commit.

Change-Id: I78fbd3ec32c02e2b080c3ee64c6bb36218930a84
Merge "Adding Wikivoyage to the default interwiki map"