[Docs] Update search on 18.10
[Docs] Update search on 18.10

Updating main.js to be the same as 18.09 (except for the API endpoint).

Resolves: LE-11456
Change-Id: Ia084c609ba3b965451d0ddf6d67df81adb64e7fe

legatoproject/legato-docs,legatoproject/legato-docs,legatoproject/legato-docs