[BUG] Microsoft.Authorization/stable/2023-04-01/policyDefinitions.json $filter definition is incorrect

### API Spec link

https://github.com/Azure/azure-rest-api-specs/blob/main/specification/resources/resource-manager/Microsoft.Authorization/stable/2023-04-01/policyDefinitions.json#L700

### API Spec version

2023-04-01

### Describe the bug

REST API [documentation](https://learn.microsoft.com/en-us/rest/api/policy/policy-definitions/list?view=rest-policy-2023-04-01&tabs=HTTP) states following for $filter query parameter

> If $filter='category -eq {value}' is provided, the returned list only includes all policy definitions whose category match the {value}.

Let's filtering syntax available on the documentation

```powershell
$x = Invoke-AzRestMethod -Path "/subscriptions/${subscriptionId}/providers/Microsoft.Authorization/policyDefinitions?api-version=2023-04-01&`$filter='category -eq SQL'"
$x.StatusCode
# returns 404
```

Let's try other filtering syntax from other endpoints:

```powershell
$x = Invoke-AzRestMethod -Path "/subscriptions/${subscriptionId}/providers/Microsoft.Authorization/policyDefinitions?api-version=2023-04-01&`$filter=category eq 'SQL'"
$x.StatusCode
# returns 200
($x.Content | ConvertFrom-Json).value.Count
# returns 80 (policy definitions)
```

### Expected behavior

Documentation should be correct and if possible provide working examples.

### Actual behavior

$filter directive given is the documentation does not match with reality and at least filter by category does not work. Did not test other filter types

### Reproduction Steps

In the description

### Environment

N/A. Calling REST API directly.