Fix Search Feature

First, the mkdocs search plugin should be enabled,

plugins:
- search

Then, it needs to be wired up.

{%- block search_button %}
{%- if 'search' in config['plugins'] %}
<div id="book-search-input" role="search">
<input type="text" placeholder="Type to search" />
</div> <!-- end of book-search-input -->
{%- endif %}
{%- endblock %}

Source: base.html

GitBook uses javascript to dynamically generate the views, but I'm faking it by using a practically empty push script,

var gitbook = gitbook || [];
gitbook.push(function() {
    gitbook.page.hasChanged({
        "page": {},
        "config": {},
        "file": {},
        "gitbook": {
            "version": "3.2.3",
            "time": "2018-06-16T01:44:55.224Z"
        },
        "basePath": ".",
        "book": {
            "language": ""
        }
    });
});

Source: js/main.js

I haven't really figured out how to get it to work yet, so for now I have it disabled.