docs(release): generate 3.8.0 changelog (#13532)

[kikito]

Co-authored-by: Qi [email protected]

Summary

Checklist

• The Pull Request has tests
• A changelog file has been created under changelog/unreleased/kong or skip-changelog label added on PR if changelog is unnecessary. README.md
• There is a user-facing docs PR against https://github.com/Kong/docs.konghq.com - PUT DOCS PR HERE

Issue reference

Fix #[issue number]

[team-gateway-bot]

Cherry-pick failed for master, because it was unable to cherry-pick the commit(s).

Please cherry-pick the changes locally.

git remote add upstream https://github.com/kong/kong-ee
git fetch upstream master
git worktree add -d .worktree/cherry-pick-13662-to-master-to-upstream upstream/master
cd .worktree/cherry-pick-13662-to-master-to-upstream
git checkout -b cherry-pick-13662-to-master-to-upstream
ancref=$(git merge-base 6200b1af3f63ee7827b142bf7e2c2e92eb2255f1 cf998bd8f325d825a2c1b48afb539362da8e4d37)
git cherry-pick -x $ancref..cf998bd8f325d825a2c1b48afb539362da8e4d37