add example to readme

Author: 6543

README.md

@@ -4,5 +4,41 @@
 [![Go Reference](https://pkg.go.dev/badge/github.com/urfave/cli-docs/v3.svg)](https://pkg.go.dev/github.com/urfave/cli-docs/v3)
 [![Go Report Card](https://goreportcard.com/badge/github.com/urfave/cli-docs/v3)](https://goreportcard.com/report/github.com/urfave/cli-docs/v3)
 
-urfave/cli-docs/v3 is an extended documentation library for use
-with urfave/cli/v3.
+urfave/cli-docs/v3 is an extended documentation library for use with urfave/cli/v3.
+
+## Start using
+
+1. Add the dependency to your project
+
+```sh
+ go get github.com/urfave/cli-docs/v3@latest
+ ```
+
+2. Add it as import
+
+```diff
+ import (
++  docs "github.com/urfave/cli-docs/v3"
+ )
+```
+
+3. Now use it e.g. to generate markdown docu from a command
+
+```go
+func main() {
+    app := newApp()
+    md, err := docs.ToMarkdown(app)
+    if err != nil {
+        panic(err)
+    }
+
+    fi, err := os.Create("cli-docs.md")
+    if err != nil {
+        panic(err)
+    }
+    defer fi.Close()
+    if _, err := fi.WriteString("# CLI\n\n" + md); err != nil {
+        panic(err)
+    }
+}
+```