Fix directory structure for cisco nexus 3xxx

[pavlozt]

I found a small confusion in the directory structure.
It seems that when importing old templates from the share.zabbix.com website, MS Excel was used and these names appeared.

Now there is a directory called Excel_Export and it contains a template from the NEXUS 3xxx network device
https://github.com/zabbix/community-templates/tree/main/Applications/Excel_Export

The network devices meant were Cisco Nexus 3000 series https://www.cisco.com/c/en/us/support/switches/nexus-3000-series-switches/series.html

I think this is an obvious fix for everyone. But I have no information about the template's operation with these devices.

[pavlozt]

I don't quite understand how the site works yet, but it also contains a mention of Excel.
Probably, something on the site also needs to be updated.
https://www.zabbix.com/integrations/cisco#3rd_party