Update contents.md (#9)
Update contents.md (#9)

Add closing tags to a JS code block under `enable` section.
sferoze/quilljs,sferoze/quilljs,quilljs/quill,willrowe/quill,quilljs/quill,voxmedia/quill,tim-mc/quill,voxmedia/quill,voxmedia/quill,willrowe/quill,tim-mc/quill,sferoze/quilljs,willrowe/quill,quilljs/quill,sferoze/quilljs