Update DocSearch.js to latest version

Update DocSearch.js to latest version

The latest (2.6.2) docsearch.js version now displays results as standard `<a href>` links, allowing users to `ctrl`-click on them to trigger default browser behavior of opening in a new tab.

To maintain backward compatibility, this behavior has only been enabled to users that didn't define their own `handleSelected` method.

This PR updates your `docsearch()` code to take advantage of the new `<a href>` template, by removing your custom `handleSelected` and moving its behavior to the `transformData` call. Namely, what you wanted to avoid was jumping to the first `<h1>` of the pages, which would prevent users from seeing the header. This PR checks if the suggestion targets the `#content` anchor (meaning it goes to this first `<h1>`) and remove it.

Behavior should be the same, but at least now you can enjoy the `ctrl`-click :)