Update en.text

Added a section how to print fingerprints ‒ without actually importing a key to one's keyring.This is a useful but not so well-known option.
Maybe instead of 'when' it could be "If you..."?

Also, I dont quite understand why you are saying to print the keyfile? Or are you just meaning to say that you should display the fingerprint on the screen before importing it? If so, I'd suggest a slightly different wording to make it more clear.