Add Google OmniBox support

[JohnONolan]

Allow Ghost docs to be searched directly from Chrome with Google Omnibox (eg. In the address bar type youtube.com then press tab to search YouTube)

Basic info:
https://stackoverflow.com/questions/7630144/how-to-add-google-chrome-omnibox-search-support-for-your-site

[aileen]

I started looking into this, and it seems not like an easy and quick one. The Omnibox snippet requires an URL by which the client can perform the search and request results (📖 see here.

The way we're using Algolia search currently would not work with that. Our search and search results are not being reflected in the URL and we have no way currently to change that.

In order to have OpenSearch working with Algolia, we would need to enable URL synchronization. There are instructions for this here.

This is just a little writeup of what I found so far and that it needs more looking into it, in order to add this feature.