[DOCS] Link to GitHub API permission requirements in `github_organization_webhook` docs

### Expected Behavior

This is same issue as #62 - my user has access to the organization, I'm authenticating via the `gh` CLI tool, but I get a 404.

### Actual Behavior

webhook created

### Terraform Version

Terraform v1.9.8
on linux_amd64
+ provider registry.terraform.io/hashicorp/google v6.26.0
+ provider registry.terraform.io/hashicorp/google-beta v7.2.0
+ provider registry.terraform.io/hashicorp/random v3.7.2
+ provider registry.terraform.io/integrations/github v6.6.0

### Affected Resource(s)

github_organization_webhook

### Terraform Configuration Files

```hcl
resource "github_organization_webhook" "runner-autoscaler" {
configuration {
url = local.webhookAbsURL
content_type = "application/json"
secret = random_password.webhook_org_secret.result
insecure_ssl = false
}

active = true

events = ["workflow_job"]
}
```

### Steps to Reproduce

_No response_

### Debug Output

```shell

```

### Panic Output

```shell

```

### Code of Conduct

- [x] I agree to follow this project's Code of Conduct