fix(docs): update changelog

CHANGELOG.md

@@ -1,19 +1,20 @@
 # Changelog
 
-## [unreleased]
+## v0.90
 
 ### Fixed
 
 - Alert history will now correctly handle Prometheus servers with
   `--web.external-url` containing sub-uri, see
-  [#3387](https://github.com/prymitive/karma/issues/3387)
+  [#3387](https://github.com/prymitive/karma/issues/3387).
 - Alert history queries didn't include grid labels as those got
   removed from alert groups in #3222, this is now fixed.
 
 ### Changed
 
 - Reduced CSS bundle size by removing unused CSS rules with
   [PurgeCSS](https://purgecss.com/).
+- Upgraded [bootstrap](https://getbootstrap.com/) to 5.1
 
 ## v0.89