The changes in this commit were auto-generated by running
tool/migrate.sh
Following this commit, the Dactyl build no longer works but the Redocly
build (mostly) should.
The new folder will be compatible with both Dactyl and Redocly when it
comes to loading the Japanese translation for a given page.
Snippets are not moved for now because importing them would require
more complex changes to the actual Markdown pages, and wouldn't be
cross-compatible anyway (Redocly uses slightly different 'partial'
rather than 'include' syntax.)
