[New docs] Spike: Figure out the best way to integrate full-text search into new docs

[tkajtoch]

Summary

One of the goals for the new docs site is better searchability. We want to integrate a full-text search capability into the site based on Elastic Enterprise Search, Elastic App Search, or a local index like Lunr.js

Requirements

• The chosen solution must allow the creation of separate indexes for each EUI version/release
• Indexing must happen during or up to 1-hour post docs site deployment
• It must allow extending the index to search by component prop names, export names, and others

Acceptance Criteria

• An ADR summarizing the findings and chosen solution should be approved and merged
• Follow-up implementation tickets should be created

[tkajtoch]

We decided to use lunr.js for the time being. The implementation is done and available on EUI+