Create note without alias

[sotte]

Just override the default note_frontmatter_func to not create an alias in the frontmatter:

        note_frontmatter_func = function(note)
        -- Add the title of the note as an alias.
        local out = { id = note.id, tags = note.tags }
        -- `note.metadata` contains any manually added fields in the frontmatter.
        -- So here we just make sure those fields are kept in the frontmatter.
        if note.metadata ~= nil and not vim.tbl_isempty(note.metadata) then
          for k, v in pairs(note.metadata) do
            out[k] = v
          end
        end
        return out
      end,

Inspired by this: #108