README: fix icon

README.md

@@ -2,7 +2,7 @@
 [![Installs](https://img.shields.io/flathub/downloads/com.cassidyjames.butler?label=Installs)][Flathub]
 [![Please do not theme this app](https://stopthemingmy.app/badge.svg)](https://stopthemingmy.app)
 
-![Icon](data/icons/app.svg?raw=true)
+![Icon](data/icons/release.svg?raw=true)
 
 # Butler
 
@@ -37,6 +37,8 @@ If there's more interest in making this into a better-integrated companion app f
 
 ## Developing and Building
 
+![Icon](data/icons/devel.svg?raw=true)
+
 I recommend using GNOME Builder for development.
 
 [Only on Flathub]: https://cassidyjam.es/apps#only-on-flathub