docs: add a ref for setting Disqus shortname

LocTran · web-flow · commit 0dc4d5fd9074 · 2020-09-07T18:07:08.000+08:00
diff --git a/docs/config/README.md b/docs/config/README.md
@@ -255,6 +255,8 @@ Vssue and Disqus are our built-in comment services. Here's the required properti
   clientSecret: 'Your clientSecret',
 }
 ```
+For setting the shortname for disqus, visit [here](https://help.disqus.com/en/articles/1717111-what-s-a-shortname)
+
 Further configuration, please visit:
 - [vuepress-plugin-disqus-comment](https://vuepress-plugin-disqus.netlify.com/#usage)
 - [vuepress-plugin-vssue](https://vssue.js.org/guide/vuepress.html#usage)

Original file line number	Diff line number	Diff line change
`@@ -255,6 +255,8 @@ Vssue and Disqus are our built-in comment services. Here's the required properti`
`255`	`255`	`clientSecret: 'Your clientSecret',`
`256`	`256`	`}`
`257`	`257`	```
	`258`	`+For setting the shortname for disqus, visit [here](https://help.disqus.com/en/articles/1717111-what-s-a-shortname)`
	`259`	`+`
`258`	`260`	`Further configuration, please visit:`
`259`	`261`	`- [vuepress-plugin-disqus-comment](https://vuepress-plugin-disqus.netlify.com/#usage)`
`260`	`262`	`- [vuepress-plugin-vssue](https://vssue.js.org/guide/vuepress.html#usage)`