Set up a connection to Greenhouse

API guide link: https://developers.greenhouse.io/harvest.html#introduction

Link to authentication page: https://developers.greenhouse.io/harvest.html#authentication

1. Name: Required: Name the connection.
2. Connection type: Required: The form will automatically select Greenhouse.
3. API Token: Required: Enter the API token. Use the following steps to get an API token.
   1. Log in to Greenhouse account.
   2. Click Settings>Devcenter.
   3. Click on API Credentials.
   4. The Harvest API Key is the required API Token.
4. User ID: Required: The Greenhouse user id can be obtained by using List Users API.
5. Borrow concurrency from (optional): Select another connection from the list....

6. Concurrency level (optional): Up to 25 allowed....