Visit the [theme documentation](https://matcornic.github.io/hugo-learn-doc/basics/what-is-this-hugo-theme/) to see what is going on. It is actually built with this theme.
To use the `search` functionality, you just have to put a `lunr` index which respects this format :
```json
[
{
"uri": "/docs/01-start/index",
"title": "Get started",
"content": "\n\nGet started\n\nAll you need to know...\n",
"tags": ["start", "intro"]
},
...
]
```
into a `static/json/search.json` file in your hugo project.
And set `search = true` in your config.toml
To generate your lunr index, you can see this project https://github.com/gwleclerc/lunr-hugo which parse your markdown files and extract toml and yaml headers to create index with corresponding format.