Fix incorrect doctest

Dependencies

• [2] BOFUYB6I Add documentation and implement some feedback from Discord (https://discord.com/channels/273534239310479360/354038657075904544/796256815024701480)
• [3] 5II6T7YE Add gemini library

Change contents

• replacement in gemini/src/header.rs at line 13
  [2.14812]→[2.14812:14918](∅→∅)
  − //! assert_eq!(Header::new(Status::INPUT, "Hello!".to_string()).unwrap().meta_kind(), MetaKind::Message);
  [2.14812]

  [2.14918]
  + //! assert_eq!(Header::new(Status::INPUT, "Hello!".to_string()).unwrap().meta_kind(), MetaKind::Prompt);