Add draft of lsif-go blog post

Created by: efritz

This adds a blog post about lsif-go performance improvements. It's light on technical details but still says why we care to optimize this.

This adds another blog post outside of the release cycle about the technical aspects of optimizing the indexer. This is similar to the other article(s) I did about changes to the code intel backend. I think a good number of people could find this kind of detail interesting and might get circulated in some social media (if we plug it correctly). Last attempt was a bit lukewarm, but that may have been because of a poor article framing.

Please make any suggestions about intro/outtro/detail phrasing that could make the article more interesting/more clear, and feel free to comment on the general approach.