Spectre: Integrate algolia docsearch

[m5o]

• https://github.com/algolia/docsearch
• https://community.algolia.com/docsearch/

[picturepan2]

@m5o I have signed up weeks ago. Trying to integrate it soon.

[san-kumar]

@picturepan2 Did Algolia send you the custom code? Is there anything I can help you with? Search would be great for the docs!