expose appendFile API

wkh237 · wkh237 · commit 1471ca16e289 · 2016-07-04T10:59:03.000+08:00
diff --git a/src/fs.js b/src/fs.js
@@ -316,6 +316,7 @@ export default {
   cp,
   writeStream,
   writeFile,
+  appendFile,
   readFile,
   exists,
   createFile,
