Bring 2 changes that ensure that the GitHub Action is backwards compatible:
- Append `http://` if the prefix is not provided in the `OP_CONNECT_HOST` (this is caused by the fact that `curl` guesses the protocol if not provided (https://linux.die.net/man/1/curl), which we missed when switching to using the 1Password CLI as the backend of the action)
- Set the default of export-env to true, since that was the default behavior of the action until we added the possibility to export secrets as step's output.
Also, the documentation is adjusted to reflect these changes.
This is done to be able to pass loaded secrets as output. This is not available with a composite action, unless we hard-code the action's outputs, which is not a desired outcome.
