docs(validate-pr): Add v4 advisory-mode changelog entry

Also corrects the original v3-era entry to drop the "enforcing draft
status" language — that part of the feature was removed in #159 and
never shipped in a tagged release.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: stephanie-anderson

CHANGELOG.md

@@ -2,9 +2,14 @@
 
 ## Unreleased
 
+### Breaking changes
+
+- Validate PR - Major v4 release: action is now advisory. PRs are no longer closed, and no labels are applied. Instead, a single friendly comment is posted on community PRs that don't reference an issue with maintainer discussion. The `was-closed` output has been removed. Recommended trigger is now `types: [opened]` (drop `reopened`). Pin to `@v3` to keep the previous closing behavior.
+
 ### Features
 
-- Add validate-pr composite action for validating non-maintainer PRs against contribution guidelines and enforcing draft status ([#153](https://github.com/getsentry/github-workflows/pull/153))
+- Validate PR - Skip validation for PRs with fewer than 100 lines changed, excluding common lock files (`Cargo.lock`, `yarn.lock`, `package-lock.json`, `Pipfile.lock`, etc.). Tiny PRs no longer go through the issue-discussion loop.
+- Add validate-pr composite action for validating non-maintainer PRs against contribution guidelines ([#153](https://github.com/getsentry/github-workflows/pull/153))
 
 ## 3.3.0