Highlight.js console deprecation logs.

[HarshKapadia2]

• Highlight.js outputs the following in the console.
  • Deprecated as of 10.7.0. highlightBlock will be removed entirely in v12.0
  • Deprecated as of 10.7.0. Please use highlightElement now.
• Handle this and make necessary changes.
  • Might have to raise an issue on the Asciidoctor repo.