The documentation part "8 Template changes" (https://www.zabbix.com/documentation/4.0/manual/installation/template_changes) describes the following:
<snip>
This page lists all changes to the stock templates that are shipped with Zabbix. It is suggested to modify these templates in existing installations - depending on the changes, it can be done either by importing the latest official version or by performing the change manually.
<snip>

But, on the one hand the template changes are not fully described, so manual changes in existing installations could not exactly be made and on the other hand the changed templates could not be found on https://share.zabbix.com.

So, we need an advice how a existing installation can get the changes in the stock templates !!

We also created a Zabbix forum entry (https://www.zabbix.com/forum/zabbix-help/376280-where-can-i-find-changed-updated-official-templates) but there were not helpful answers.