docs: fix url to demo instance (#961)

Author: PTrottier

packages/docs/content/docs/configuration-options.mdx

@@ -15,7 +15,7 @@ Alternatively, you can specify a custom config file using a link tag:
 
 If you prefer, you can use a javascript file (`admin/config.js`) instead of a yaml file. Simply import the javascript config and pass it into your `CMS.init({ config })` call.
 
-To see working configuration examples, you can [start from a template](/docs/start-with-a-template) or check out the [CMS demo site](https://demo-staticcms.org/). (No login required: click the login button and Static CMS will open.) You can refer to the demo [configuration code](https://github.com/StaticJsCMS/static-cms/blob/main/core/dev-test/config.yml) to see how each option was configured.
+To see working configuration examples, you can [start from a template](/docs/start-with-a-template) or check out the [CMS demo site](https://demo.staticcms.org/). (No login required: click the login button and Static CMS will open.) You can refer to the demo [configuration code](https://github.com/StaticJsCMS/static-cms/blob/main/core/dev-test/config.yml) to see how each option was configured.
 
 You can find details about all configuration options below. Note that [YAML syntax](https://en.wikipedia.org/wiki/YAML#Basic_components) allows lists and objects to be written in block or inline style, and the code samples below include a mix of both.
 

packages/docs/content/docs/test-backend.mdx

@@ -6,7 +6,7 @@ weight: 60
 
 - **Name**: `gitlab`
 
-You can use the `test-repo` backend to try out Static CMS without connecting to a Git repo. With this backend, you can write and publish content normally, but any changes will disappear when you reload the page. This backend powers the Static CMS [demo site](https://demo-staticcms.org/).
+You can use the `test-repo` backend to try out Static CMS without connecting to a Git repo. With this backend, you can write and publish content normally, but any changes will disappear when you reload the page. This backend powers the Static CMS [demo site](https://demo.staticcms.org/).
 
 **Note:** The `test-repo` backend can't access your local file system, nor does it connect to a Git repo, thus you won't see any existing files while using it.