update reademe

README.md

@@ -1,5 +1,28 @@
 `gosh` eine einfache Shell, geschrieben in golang.
 
+```
+gosh - Go Shell
+
+Built-in commands:
+  cd [dir]       - Change directory (cd with no args goes to home)
+  pwd           - Print working directory
+  echo [args]   - Echo arguments
+  exit [code]   - Exit shell with optional status code
+  quit [code]   - Quit shell with optional status code
+  set VAR=val   - Set environment variable
+  export VAR=val - Export environment variable
+  help          - Show this help
+
+Features:
+  - Argument parsing with quotes and escapes
+  - Ctrl+D to exit, Ctrl+C to cancel
+  - Command history (up/down arrows)
+  - Tab completion for commands and file paths
+  - Tilde expansion (~, ~/path)
+  - Environment variable expansion ($VAR, ${VAR})
+
+```
+
 ## building
 
 ```bash