doc: describe more the project

Author: sylvestre

README.md

@@ -42,9 +42,16 @@ cargo install coreutils
 
 ## Goals
 
-uutils aims to be a drop-in replacement for the GNU utils. Differences with GNU
+uutils coreutils aims to be a drop-in replacement for the GNU utils. Differences with GNU
 are treated as bugs.
 
+Our key objectives include:
+- Matching GNU's output (stdout and error code) exactly
+- Better error messages
+- Providing comprehensive internationalization support (UTF-8)
+- Improved performances
+- [Extensions](docs/src/extensions.md) when relevant (example: --progress)
+
 uutils aims to work on as many platforms as possible, to be able to use the same
 utils on Linux, macOS, Windows and other platforms. This ensures, for example,
 that scripts can be easily transferred between platforms.