add cli example

Author: Dean Karn

README.md

@@ -38,7 +38,13 @@ func main() {
 	}
 	fmt.Printf("%v\n", result)
 }
+```
 
+#### CLI Usage
+```shell
+~ ksql '(.field1 + 1) /2' '{"field1": 1}'
+or
+echo '{"field1": 1}' | ksql '(.field1 + 1) /2'
 ```
 
 #### Expressions