Change description of Brave Search to be fully independent

[yuuz233]

As in their announcement, Brave Search is now fully independent and not relied on BigTech search engine results. Thus, the description of "which for the most part doesn't rely on search engines like Google or Bing, but falls back on them if not enough results are found" is no longer accurate and should be removed.

[meatspinner]

They don't have image search for now though, they redirect to either Bing or Google, so they aren't really fully independent (IMO).