misc(seo) fix sitemap to not mention index.html for each page

Author: EugeneHlushko

package.json

@@ -45,7 +45,7 @@
     "lint:prose": "cp .proselintrc ~/ && proselint src/content",
     "lint:links": "hyperlink -r dist/index.html --canonicalroot https://webpack.js.org/ -i --todo https://img.shields.io --todo https://codecov.io/gh --todo 'content-type-mismatch https://travis-ci.org' --todo 'Asset is used as both Html and Image' | tee internal-links.tap | tap-spot",
     "linkcheck": "hyperlink -r dist/index.html --canonicalroot https://webpack.js.org/ --skip support__ --skip sidecar.gitter.im --skip vimdoc.sourceforge.net --skip img.shields.io --skip npmjs.com/package/ --skip opencollective.com/webpack --todo external-redirect | tee external-links.tap | tap-spot",
-    "sitemap": "cd dist && sitemap-static --prefix=https://webpack.js.org/ > sitemap.xml",
+    "sitemap": "cd dist && sitemap-static --pretty --prefix=https://webpack.js.org/ > sitemap.xml",
     "serve": "npm run build && sirv start ./dist --port 4000",
     "deploy": "gh-pages -d dist"
   },