[Docs] Suggest passphrase instead of password during keygen

When generating a key, suggest using a pass phrase instead of a password (horse battery staple correct style).

Start by locating the key-generation prompt or documentation text referenced by the issue; the payload names no file or test. Update the guidance to recommend a passphrase rather than a password, using the “horse battery staple” style example, and verify that the revised wording appears during key generation.

Written by the indexing model from the issue text.