Improve usage

README.md

@@ -2,14 +2,31 @@
 
 cueimports is a [CUE](https://github.com/cue-lang/cue) tool that updates your import lines, adding missing ones and removing unused ones.
 
+It scans through:
+
+- your local packages
+- the cue.mod directory packages
+- the standard library packages
+
 ## Install
 
-```
+```bash
 go install github.com/asdine/cueimports/cmd/cueimports
 ```
 
 ## Usage
 
 ```bash
-cueimports [path ...]
+$ echo "data: json.Marshal({a: math.Sqrt(7)})" | cueimports
+```
+
+```
+package hello
+
+import (
+	"encoding/json"
+	"math"
+)
+
+data: json.Marshal({a: math.Sqrt(7)})
 ```