Zoekt for code search - Readiness Review

Readiness review for:

1. #65 (closed)
2. https://docs.gitlab.com/ee/architecture/blueprints/code_search_with_zoekt/

View rendered markdown at https://gitlab.com/gitlab-com/gl-infra/readiness/-/blob/zoekt-code-search-readiness/zoekt-code-search/index.md