Update .npmignore

[jherdman]

Far too much is being published.

[arve0]

Thanks. Released in [email protected]:

npm notice 
npm notice 📦  [email protected]
npm notice === Tarball Contents === 
npm notice 621B   .eslintrc.json              
npm notice 19B    .gitattributes              
npm notice 1.1kB  LICENSE                     
npm notice 6.4kB  README.md                   
npm notice 322B   debug.js                    
npm notice 207B   demo.js                     
npm notice 4.0kB  index.js                    
npm notice 22.9kB markdown-it-attrs.browser.js
npm notice 1.6kB  package.json                
npm notice 9.6kB  patterns.js                 
npm notice 7.6kB  utils.js                    
npm notice === Tarball Details === 
npm notice name:          markdown-it-attrs                       
npm notice version:       4.1.1                                   
npm notice filename:      markdown-it-attrs-4.1.1.tgz             
npm notice package size:  12.0 kB                                 
npm notice unpacked size: 54.5 kB                                 
npm notice shasum:        1c0a102d9cf1882642b58c236ad70b61cf3d9d91
npm notice integrity:     sha512-0nyjVuj4KHbNh[...]5ggPW932NE6zQ==
npm notice total files:   11