Merge pull request #415 from leancloud/update-readme

docs: typos and outdated icons in README

Author: zapcannon87

README.md

@@ -1,7 +1,6 @@
 # LeanCloud Swift SDK
 
-[![Build Status](https://travis-ci.org/leancloud/swift-sdk.svg?branch=master)](https://travis-ci.org/leancloud/swift-sdk)
-[![Coverage Status](https://coveralls.io/repos/github/leancloud/swift-sdk/badge.svg?branch=master)](https://coveralls.io/github/leancloud/swift-sdk?branch=master)
+![Build Status](https://github.com/leancloud/swift-sdk/workflows/Release%20Drafter/badge.svg)
 
 ## Features
   * [x] Data Storage
@@ -17,6 +16,8 @@
   * If you **found a bug**, open an issue, or open a ticket in [LeanTicket][LeanTicket].
   * If you **want to contribute**, submit a pull request.
 
+[LeanTicket]: https://leanticket.cn/
+
 ## Installation & Quick Start
 
 Please read [this documentation][doc].