Fixing URL used for search

The current search is using the URL "<site>/search", which is getting
redirected to the true location "<site>/search/". When running through
Hugo, the server it runs on localhost is maintaining the GET request
across the redirect, the hosting isn't.

The easiest (and arguably best) way or dealing with this is to correct the
URL so that no redirect is needed.

Signed-off-by: Martyn Welch <martyn.welch@collabora.com>