message: Update manifest.md
  Another alterations after pondering further
diff: @@ -131,7 +131,7 @@ suites, benchmarks, binaries, examples, etc.
  edition = '2018'
  ```
  -If the `edition` key is not set in your `Cargo.toml` file, Cargo will default to 2015.
  +If the `edition` key is not set, or the value is not a valid [Rust edition] in your `Cargo.toml`, Cargo will default to 2015.
  #### The `description` field
  