Steps to reproduce:

1. Go to page https://www.zabbix.com/documentation/current/en/manual/config/items/itemtypes/simple_checks/vmware_keys
2. Scroll down to The performance counter group descriptions, counter names and rollup types can be found in VMware documentation.
3. Click on link [VMware documentation
4.  

Result:
Link redirect on landing page of VMware Documentation portal

After a chat with VMware support team, needed information was found at https://developer.vmware.com/apis/968 (vSphere Web Services API \ Managed object types \ PerformanceManager). Direct link is https://vdc-download.vmware.com/vmwb-repository/dcr-public/b50dcbbf-051d-4204-a3e7-e1b618c1e384/538cf2ec-b34f-4bae-a332-3820ef9e7773/vim.PerformanceManager.html but i suspect it may change