variables.json: add a variable for TiDB Cloud console URL (pingcap#21450)

Author: qiancai

develop/dev-guide-sample-application-python-peewee.md

@@ -74,7 +74,7 @@ Connect to your TiDB cluster depending on the TiDB deployment option you've sele
 <SimpleTab>
 <div label="{{{ .starter }}}">
 
-1. Navigate to the [**Clusters**](https://tidbcloud.com/console/clusters) page, and then click the name of your target cluster to go to its overview page.
+1. Navigate to the [**Clusters**](https://{{{.console-url}}}/project/clusters) page, and then click the name of your target cluster to go to its overview page.
 
 2. Click **Connect** in the upper-right corner. A connection dialog is displayed.
 

variables.json

@@ -4,5 +4,6 @@
   "self-managed": "TiDB Self-Managed",
   "starter": "TiDB Cloud Serverless",
   "essential": "TiDB Cloud Essential",
-  "dedicated": "TiDB Cloud Dedicated"
-}
+  "dedicated": "TiDB Cloud Dedicated",
+  "console-url": "tidbcloud.com"
+}