add shellcheck badge

.github/workflows/shellcheck.yml

@@ -1,4 +1,4 @@
-name: CI
+name: shellcheck
 on: [push, pull_request]
 
 jobs:

README.md

@@ -1,9 +1,10 @@
 # An ACME Shell script: acme.sh [![Build Status](https://travis-ci.org/acmesh-official/acme.sh.svg?branch=master)](https://travis-ci.org/acmesh-official/acme.sh)
 
-<a href="https://opencollective.com/acmesh" alt="Financial Contributors on Open Collective"><img src="https://opencollective.com/acmesh/all/badge.svg?label=financial+contributors" /></a> [![Join the chat at https://gitter.im/acme-sh/Lobby](https://badges.gitter.im/acme-sh/Lobby.svg)](https://gitter.im/acme-sh/Lobby?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
+<a href="https://opencollective.com/acmesh" alt="Financial Contributors on Open Collective"><img src="https://opencollective.com/acmesh/all/badge.svg?label=financial+contributors" /></a> 
+[![Join the chat at https://gitter.im/acme-sh/Lobby](https://badges.gitter.im/acme-sh/Lobby.svg)](https://gitter.im/acme-sh/Lobby?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
 [![Docker stars](https://img.shields.io/docker/stars/neilpang/acme.sh.svg)](https://hub.docker.com/r/neilpang/acme.sh "Click to view the image on Docker Hub")
 [![Docker pulls](https://img.shields.io/docker/pulls/neilpang/acme.sh.svg)](https://hub.docker.com/r/neilpang/acme.sh "Click to view the image on Docker Hub")
-
+![shellcheck](https://github.com/acmesh-official/acme.sh/workflows/shellcheck/badge.svg)
 
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