docs(CHANGELOG): Minor cleanup

[andyleiserson]

• Fixes a couple PR link placeholders to link to the actual PRs.
• Remove "BREAKING CHANGE" from the depth/stencil changes in the major changes section, since none of the others have it, I guess it's assumed that major changes are likely breaking?
• Remove entry for Tweak some limit reporting #9118 because it is obsoleted by the entry for Fix limit reporting #9196.

Squash or Rebase? Squash

[cwfitzgerald]

Thanks!