documentation: provide autocompletion in UTF-8 as well.

documentation: provide autocompletion in UTF-8 as well.

The search() function returns the result list in UTF-8, but the
autocompletion was not. And of course renderResults() assumed it was in
UTF-8 and decoded it from UTF-8 *twice*. This wasn't discovered until
now because I had no pages with UTF-8 names apart from the test (which
doesn't test the UI stuff).