Recipe: per-vault spellfile in vault root

[neo451]

vim.api.nvim_create_autocmd("User", {
      pattern = "ObsidianNoteEnter",
      callback = function()
         local note = obsidian.api.current_note()
         local spellfile = Obsidian.workspace.root / ".en.utf-8.add"
         if not spellfile:exists() then
            vim.fn.writefile({}, tostring(spellfile))
         end
         vim.bo[note.bufnr].spellfile = tostring(spellfile)
   end
})

helpful for if you want to keep dictionaries separate

TODO: use or append obsidian app's global dictionary? stored in .config/obsidian/Custom DIctionary.txt