How to display the related documents in a tab next to the fields?

In order to display the related documents in a tab, you must go to the basic settings of the form and activate the option "Show related documents in tab".

Once enabled, every time you go to a document using that form, the "Related documents" tab will appear as shown in the screenshot below. If the document is an email, this tab will always be displayed automatically so that you can see the email attachments.