Improve documentation for password protected pem files

Hello!
I have a a registered app on an enterprise account.
My Dev team uses both R and Python.
I'm trying to adapt the Python code to use AzureAuth, but I'm hitting a wall with documentation and error messages.

Variables I have:
- Tenant ID
- Client ID (app id)
- Thumbprint
- pem file
- password to unlock pem file

When I try the code below (trying both the absolute file name and the path to the file) I get this error:
`Error in read_input(file) : file must be connection, raw vector or file path`

It's also unclear where to enter the `pem` **password** or the **thumbprint**.

Could you please provide a vignette for a password protected pem file and thumbprint?

```

resource <-"https://graph.microsoft.com/.default"
cert_path <- "C:/Users//Documents/repo_work/api_r_demo/CHCAnalyticsAutomation.pem"

get_azure_token(resource,
creds$TENANT_ID,
creds$CLIENT_ID,
certificate=cert_path,
auth_type="client_credentials")
```