text: Title: Update docs to indicate that API values of []byte are always base64-encoded
  Body: <!-- Please only use this template for submitting enhancement requests -->
  
  **What would you like to be added**:
  Extend the docs the clarify that various places there the API expects `[]byte` that this is base64 encoded
  
  **Why is this needed**:
  I was looking at the 1.13 API docs for the conversion webhook and it said
  
  ```
  `caBundle` is a PEM encoded CA bundle which will be used to validate the webhook's server certificate. If unspecified, system trust roots on the apiserver are used.
  ```
  
  It's not obvious to me that this value should be base64 of the pem encoded contents
  
  <!-- DO NOT EDIT BELOW THIS LINE -->
  /kind feature