I am a manager of sdet, testing and release Management. I have managed release of more than 20 softwares and have a team of 10+ engineers.

I am looking to get into software engineering manager role. 

Any advice on resources that I can use online to identify what things I should learn to get there? Where can I learn them? 

I do feel like I'm hitting the ceiling as an engineer and will again do so as a manager. How can use this to prepare myself for the step after getting into software engineering management?