2: Add solution to Rust track exercise "Hello World".

Dependencies

• [2] OSLWPPDF 1: Add Rust track exercise "Hello World".

Change contents

• replacement in rust/hello-world/tests/hello-world.rs at line 3
  [2.131]→[2.131:186](∅→∅)
  − assert_eq!("Hello, World!", hello_world::hello());
  [2.131]

  [2.186]
  + assert_eq!("Hello, World!", hello_world::hello());
• replacement in rust/hello-world/src/lib.rs at line 3
  [2.349]→[2.349:370](∅→∅)
  − "Goodbye, Mars!"
  [2.349]

  [2.370]
  + "Hello, World!"