Here is the guide about 'How to send Pull Request to the Staging Team liferay-staging':https://liferay.atlassian.net/wiki/spaces/ENGSTAGING/pages/1892090522/How+to+send+Pull+Request+to+the+Staging+Team+liferay-staging#For-the-Staging-Team
Here is a template you should use when you send a PR to the liferay-staging' user: https://liferay.atlassian.net/wiki/spaces/ENGAPPSECURITY/pages/2289861613/Pull+request+template
Here is the introduction of Staging Team: https://liferay.atlassian.net/wiki/spaces/ENGSTAGING/overview?homepageId=1266155696