docs: add document for compressed writer

README.md

@@ -117,6 +117,7 @@ following are some shots:
 
 - [Standard Writer](./writer/standard/README.md), prints QRCode into file and stream
 - [Terminal Writer](./writer/terminal/README.md), prints QRCode into terminal
+- [Compressed Writer](./writer/compressed/README.md), It's generated on a very small scale
 
 Of course, you can also code your own writer, just implement [Writer](./writer/README.md) interface.
 

writer/compressed/README.md

@@ -0,0 +1,27 @@
+## Compressed Writer
+
+[![go.dev reference](https://img.shields.io/badge/go.dev-reference-007d9c?logo=go&logoColor=white&style=flat-square)](https://pkg.go.dev/github.com/yeqown/go-qrcode/writer/compressed)
+
+Compressed Writer is a writer that is used to draw QR Code image on a very small scale.
+Since the compressed writer would only use a two-tone palette to generate the image,
+and automatically compressed in PNG format.
+
+Check codes for more details about compress principle.
+
+### Usage
+
+```go
+option := compressed.Option{
+	Padding:   4, // padding pixels around the qr code.
+	BlockSize: 1, // block pixels which represents a bit data.
+}
+
+w, err := compressed.New(name, &option)
+	if err != nil {
+	panic(err)
+}
+
+if err := qrc.Save(w); err != nil {
+	panic(err)
+}
+```