message: Add note about minimum Rust version to README.
diff: @@ -50,7 +50,7 @@ Criterion.<span></span>rs helps you write fast code by detecting and measuring p
  ### Quickstart
  -In order to generate plots, you must have [gnuplot](http://www.gnuplot.info/) installed. See the gnuplot website for installation instructions.
  +In order to generate plots, you must have [gnuplot](http://www.gnuplot.info/) installed. See the gnuplot website for installation instructions. Criterion.rs also currently requires Rust 1.23 or later.
  To start with Criterion.<span></span>rs, add the following to your `Cargo.toml` file:
  