[Doc] Usage Types update

### problem

Usage types in the docs is not in sync with the list usagetypes API response / code.

Check / Update the usage types in the doc here: https://docs.cloudstack.apache.org/en/latest/adminguide/usage.html#usage-types.

list usagetypes API response =>
```
(usageenv) 🐱 > list usagetypes
{
"count": 25,
"usagetype": [
{
"description": "Running Vm Usage",
"usagetypeid": 1
},
{
"description": "Allocated Vm Usage",
"usagetypeid": 2
},
{
"description": "IP Address Usage",
"usagetypeid": 3
},
{
"description": "Network Usage (Bytes Sent)",
"usagetypeid": 4
},
{
"description": "Network Usage (Bytes Received)",
"usagetypeid": 5
},
{
"description": "Volume Usage",
"usagetypeid": 6
},
{
"description": "Template Usage",
"usagetypeid": 7
},
{
"description": "ISO Usage",
"usagetypeid": 8
},
{
"description": "Snapshot Usage",
"usagetypeid": 9
},
{
"description": "Security Group Usage",
"usagetypeid": 10
},
{
"description": "Load Balancer Usage",
"usagetypeid": 11
},
{
"description": "Port Forwarding Usage",
"usagetypeid": 12
},
{
"description": "Network Offering Usage",
"usagetypeid": 13
},
{
"description": "VPN users usage",
"usagetypeid": 14
},
{
"description": "VM Disk usage(I/O Read)",
"usagetypeid": 21
},
{
"description": "VM Disk usage(I/O Write)",
"usagetypeid": 22
},
{
"description": "VM Disk usage(Bytes Read)",
"usagetypeid": 23
},
{
"description": "VM Disk usage(Bytes Write)",
"usagetypeid": 24
},
{
"description": "VM Snapshot storage usage",
"usagetypeid": 25
},
{
"description": "Volume on secondary storage usage",
"usagetypeid": 26
},
{
"description": "VM Snapshot on primary storage usage",
"usagetypeid": 27
},
{
"description": "Backup storage usage",
"usagetypeid": 28
},
{
"description": "Bucket storage usage",
"usagetypeid": 29
},
{
"description": "Network usage",
"usagetypeid": 30
},
{
"description": "VPC usage",
"usagetypeid": 31
}
]
}
(usageenv) 🐱 >
```

https://github.com/apache/cloudstack/blob/39c5641cbe674b19bc77082b850565f634a7cb84/api/src/main/java/org/apache/cloudstack/usage/UsageTypes.java#L24-L50

### versions

4.19.1 / 4.20.0

Start with the usage types section at docs.cloudstack.apache.org/en/latest/adminguide/usage.html#usage-types and compare it with the list usagetypes response and UsageTypes.java. Update the documentation so the listed usage types match the 25 API entries, then verify the rendered section is complete and accurate.

Written by the indexing model from the issue text.