update readme

README.md

@@ -110,6 +110,54 @@ firstIP, err := cfg.GetString("allowed_ips.0")
 username, err := cfg.GetString("database.credentials.username")
 ```
 
+## Writing Data
+
+Fin supports writing data back to its format, allowing you to create or modify data at runtime:
+
+```go
+package main
+
+import (
+    "os"
+    "git.sharkk.net/Sharkk/Fin"
+)
+
+func main() {
+    // Create new data structure
+    data := fin.NewData()
+
+    // Set values
+    data.GetData()["server"] = map[string]any{
+        "host": "localhost",
+        "port": 8080,
+    }
+    data.GetData()["debug"] = true
+    data.GetData()["allowed_ips"] = []any{
+        "192.168.1.1",
+        "10.0.0.1",
+    }
+
+    // Write to file
+    file, err := os.Create("config.conf")
+    if err != nil {
+        panic(err)
+    }
+    defer file.Close()
+
+    // Use the Write method
+    err = data.Write(file)
+    if err != nil {
+        panic(err)
+    }
+
+    // Or use the standalone Save function
+    err = fin.Save(file, data)
+    if err != nil {
+        panic(err)
+    }
+}
+```
+
 ## Performance
 
 Fin goes blow-for-blow against Go's standard JSON library, and performs incredibly versus