Clarify leaving PRs open

docs/source/contributor-guide/index.md

@@ -77,7 +77,7 @@ The lifecycle of a PR is:
 1. Create a PR targeting the `main` branch.
 2. For returning contributors, CI tests are automatically run. For new contributors a committer must first trigger the tests.
 3. Your PR will be reviewed. Please respond to all feedback on the PR: you don't have to change the code, but you should acknowledge the feedback.
-4. Once the PR is approved, one of the [committers] will merge your PR, typically within 24 hours. We leave approved PRs open for some time to allow for additional feedback from the community.
+4. Once the PR is approved, one of the [committers] will merge your PR, typically within 24 hours. We leave approved "major" changes (see below) open for 24 hours prior to merging, and sometimes leave "minor" PRs open for the same time to permit additional feedback.
 
 [committers]: https://people.apache.org/phonebook.html?unix=datafusion