- Minor improvements to the documentation for snapshotting.
- Add newlines to printed errors where necessary.

Change-Id: I822e7e850adb67eae73b51c23cf34e40ba3106f0
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2144954Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Commit-Queue: Toon Verwaest <verwaest@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67111}