message: Add rethemendex as script for easier access
diff: "scripts": {
  "reskindex": "node scripts/reskindex.js -h header",
  "reskindex:watch": "node scripts/reskindex.js -h header -w",
  + "rethemendex": "res/css/rethemendex.sh",
  "i18n": "matrix-gen-i18n",
  "prunei18n": "matrix-prune-i18n",
  "build": "npm run reskindex && npm run start:init",
  