clarify blot children, closes #1825
clarify blot children, closes #1825

willrowe/quill,voxmedia/quill,sferoze/quilljs,willrowe/quill,quilljs/quill,sferoze/quilljs,quilljs/quill,sferoze/quilljs,voxmedia/quill,voxmedia/quill,willrowe/quill,sferoze/quilljs,quilljs/quill