Update MAINTAINERS.md (#736)

Move @chalin back to active maintainers, even if contributions will be less frequent.

Author: chalin

MAINTAINERS.md

@@ -2,14 +2,14 @@
 
 The active maintainers of this repository (in alphabetical order) are:
 
+- [chalin](https://github.com/chalin), Linux Foundation
 - [srini100](https://github.com/srini100), Google
 - [thisisnotapril](https://github.com/thisisnotapril), Google
 
 # Emeritus maintainers
 
 The emeritus maintainers of this repository (in alphabetical order) are:
 
-- [chalin](https://github.com/chalin), Linux Foundation
 - [lucperkins](https://github.com/lucperkins), Linux Foundation
 
 # Notes