Add support for labels and search

1. Support for label
   • getLabels()
   • postLabels()
   • deleteLabel()
   • thank you to @mlersch for adding this feature
2. Support for search
   • search()
   • thank you to @evgeniusorg for adding this feature
3. Support for field minorEdit on putContent method
   • thank you to @arthmoeros for adding this feature
4. Added jsdoc-to-markdown and support script npm run create-docs