Changelog: Add info about poll view changes

CHANGELOG.md

@@ -30,6 +30,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 - Users with the `discoverable` field set to false will not show up in searches.
 - Minimum lifetime for ephmeral activities changed to 10 minutes and made configurable (`:min_lifetime` option).
 - Introduced optional dependencies on `ffmpeg`, `ImageMagick`, `exiftool` software packages. Please refer to `docs/installation/optional/media_graphics_packages.md`.
+- Polls now always return a `voters_count`, even if they are single-choice
 
 <details>
   <summary>API Changes</summary>