text: Title: helping users when setting their key
  Body: I got a report from a cloud user that they had a "malformed API key error", somewhere in our docs, we have the following instructions:
  
  ```sh
  ploomber cloud set-key {your-key}
  ```
  
  And the user was setting it with the `{}` characters. We should detect if the passed key begins with `{` and ends with `}`. If so, ignore those characters (or maybe show an error telling them to remove them?)