Re-introduce grouping of heading options in type menu
Re-introduce grouping of heading options in type menu

tzuhsiulin/prosemirror,kiejo/prosemirror,salzhrani/prosemirror,tzuhsiulin/prosemirror,salzhrani/prosemirror,kiejo/prosemirror,tzuhsiulin/prosemirror,kiejo/prosemirror,salzhrani/prosemirror