docs/zoho: add a section explaining client_id setup

docs/content/zoho.md

@@ -234,3 +234,15 @@ Properties:
 - Default:     Del,Ctl,InvalidUtf8
 
 {{< rem autogenerated options stop >}}
+
+## Setting up your own client_id
+
+For Zoho we advise you to set up your own client_id. To do so you have to complete the following steps.
+
+1. Log in to the [Zoho API Console](https://api-console.zoho.com)
+
+2. Create a new client of type "Server-based Application". The name and website don't matter, but you must add the redirect URL `http://localhost:53682/`.
+
+3. Once the client is created, you can go to the settings tab and enable it in other regions.
+
+The client id and client secret can now be used with rclone.