Documentation: more updates to site/dev/testing/xsan.md

No-Try: true
Docs-Preview: https://skia.org/dev/testing/xsan?cl=167393
Change-Id: I5b2a992c762221e45ea3e9dcfb97cc06a86e9bc5
Reviewed-on: https://skia-review.googlesource.com/c/167393
Commit-Queue: Hal Canary <halcanary@google.com>
Reviewed-by: Kevin Lubick <kjlubick@google.com>
1 file changed