Add simple example of field renaming.

Fixes #122.

README.md

@@ -67,7 +67,10 @@ b:
 
 type T struct {
         A string
-        B struct{C int; D []int ",flow"}
+        B struct {
+                RenamedC int   `yaml:"c"`
+                D        []int `yaml:",flow"`
+        }
 }
 
 func main() {