A lack of changelogs appears to be a common theme with some apps nowadays, and the most recent culprits are Facebook Messenger and Skype for Windows Phone. Both apps have received updates, but left out changelogs — so don't expect anything in the way of major new features.
That being said, it's likely that both apps have received a decent helping of minor bug fixes and performance improvements, neither of which is a bad thing. If you'd like to pick up the most recent updates, you can grab them from the store links below. If you happen to notice anything new and notable, be sure to shout it out in the comments below. Happy updating!
Thanks for the tips, everyone!