Log in to cdswctl

Provides steps to log in to cdswctl.

Open the Model CLI client.
Run the following command while specifying the actual values for the variables:
```
cdswctl login -u <workspace_url> -n <username> -y <legacy_api_key>
```
where
- workspace_url is the workspace URL including the protocol (http(s)://domain.com)
- username is your user name on the workspace
- api_key is the Legacy API key that you can obtain from the CDSW web UI. Go to Settings > API Keys > and copy the Legacy API Key (and not the Model API Key).
A Login succeeded message is displayed.
To see more information about the login command parameters, run
```
cdswctl login --help
```