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

Dependencies

• [2] ERE2X4MY 1: Add Rust track exercise "Hello World".

Change contents

• replacement in rust/hello-world/tests/hello-world.rs at line 3
  [2.134]→[2.134:189](∅→∅)
  − assert_eq!("Hello, World!", hello_world::hello());
  [2.134]

  [2.189]
  + assert_eq!("Hello, World!", hello_world::hello());
• replacement in rust/hello-world/src/lib.rs at line 3
  [2.353]→[2.353:374](∅→∅)
  − "Goodbye, Mars!"
  [2.353]

  [2.374]
  + "Hello, World!"