General demo improvements — May 5, 2020

[zumwalt]

This PR makes a few changes in order to improve the demo experience:

• It greatly reduces the total number of documents by removing all non-current documentation
• It introduces a clicks field to elastic-co-docs documents
• It replaces the Elastic logo with a generic logo
• It simplifies styling all around
  • A single result style for both sources
  • Drops badges in favor of tags inline with the URL. This should help with rendering long document titles
  • Improves layout flexibility to account for long facet labels
  • Adds facet counts
  • Improves the highlight style and adds highlighting to the body of results