renamed games folder to entries folder (also contained frameworks, libraries, ...) and added to the backlog

entries/etterna.md

@@ -0,0 +1,17 @@
+# Etterna
+
+_Rhythm game focused on keyboard play._
+
+- Home: https://etternaonline.com/
+- State: beta
+- Download: https://github.com/etternagame/etterna/releases
+- Platform: Windows, macOS
+- Keywords: music
+- Code repository: https://github.com/etternagame/etterna.git
+- Code language: C, C++, Lua
+- Code license: MIT
+
+## Building
+
+- Build system: CMake
+