message: Update README.md
  Nightly is required for compiling
diff: @@ -63,7 +63,7 @@ software evolves: iterate, deploy, study, repeat.
  # Compile / Install Instructions
  -Rust 1.19 is the minimum requirement for compiling Ion. Simplest way to obtain Rust/Cargo is by
  +Rust nightly is required for compiling Ion. Simplest way to obtain Rust/Cargo is by
  installing the [Rustup toolchain manager](https://rustup.rs/), in the event that your OS does
  not ship Rust natively, or if you want more flexibility in Rust compilation capabilities.
  