docs: add meta description

Author: ktquez

docs/.vuepress/config.js

@@ -1,6 +1,6 @@
 module.exports = {
  title: 'Vue dark-mode',
- description: '',
+ description: 'A component that helps to implement dark mode and other color modes in your Vue application.',
  serviceWorker: true,
  head: [
  ['meta', { name: 'theme-color', content: '#fff' }],