Fix BLT's ReadTheDocs Search

[geerlingguy]

See: geerlingguy/drupal-vm#998

Basically, RTD search doesn't work out of the box currently, so if I visit http://blt.readthedocs.io/en/8.x/ and enter something in the search box, I get no results.

Applying the above fix allows the search box to return results (yay!), and is a pretty simple fix.

[geerlingguy]

Yay, it works! http://blt.readthedocs.io/en/8.x/search.html?q=architecture