Udpate changelog

Author: hasufell

changelog.md

@@ -1,6 +1,11 @@
 # Changelog for [`os-string` package](http://hackage.haskell.org/package/os-string)
 
-## 1.0.0 *??? 2023*
+## 2.0.0 *Nov 2023*
 
-* Split out `OsString` from filepath package
+* Split out `OsString` modules from filepath library
+* add more bytestring like functions (index/search/etc.)
+
+## 1.0.0 *Nov 2023*
+
+* dummy release to avoid name clashes with filepath <1.5