Comment 8 for bug 1744385

I've added my signoff branch here:
http://git.evergreen-ils.org/?p=working/Evergreen.git;a=shortlog;h=refs/heads/user/kmlussier/lp-1744385-search-highlighting-virtual-index-defs-rebased-fixes

I also turned Mike's earlier commit message into a release notes entry and made some edits/additions to that release notes entry.

We tested this branch against a fairly large set of test data. The highlighting works well, and we're getting good search results, both in terms of relevance and performance. We're looking forward to seeing this improvement in Evergreen!