chore: mention migration to Spring Boot 2.2

Part of #1149

[skip ci]

Author: php-coder

NEWS.txt

@@ -4,7 +4,8 @@
 - (infrastructure) discontinue usage of Danger
 - (infrastructure) discontinue usage of 0pdd
 - (infrastructure) migrate CI from Travis to GitHub Actions
-- (improvement) show last added series first on the pages with a collection info, series info and collection estimation
+- (improvement)    show last added series first on the pages with a collection info, series info and collection estimation
+- (infrastructure) migrate to Spring Boot 2.2
 
 0.4.6
 - (feature)        users can add a comment to a series