Update README.md

README.md

@@ -3,3 +3,46 @@
 [![GoDoc](https://godoc.org/github.com/frixuu/kdlgo?status.svg)](https://godoc.org/github.com/frixuu/kdlgo)
 
 WIP Go parser for the [KDL Document Language](https://github.com/kdl-org/kdl), version 1.0.0.
+
+## Current status
+
+- [x] parsing to a kdl.Document model
+- [x] serializing a kdl.Document model to a string
+- [ ] marshalling from a struct
+- [ ] unmarshalling to a struct
+- [ ] improve performance?
+
+## Usage
+
+```go
+import (
+	kdl "github.com/frixuu/kdlgo"
+)
+```
+
+### Parse (to a Document model)
+
+```go
+// or any of: ParseBytes, ParseFile, ParseReader
+document, err := kdl.ParseString(`foo bar="baz"`)
+```
+
+### Modify the Document
+
+```go
+if document.Nodes[0].HasProp("bar") {
+	n := kdl.NewNode("person")
+	n.AddArg("known")
+	// or: n.AddArgValue(kdl.NewStringValue("known", kdl.NoHint()))
+	n.SetProp("name", "Joe")
+	// or: n.SetPropValue("name", kdl.NewStringValue("Joe", kdl.NoHint()))
+	document.AddChild(n)
+}
+```
+
+### Serialize the Document
+
+```go
+// or Write() to an io.Writer
+s, err := document.WriteString()
+```