message: Fix unmatched backticks
diff: @@ -20,5 +20,5 @@ section in `.cargo/config`. Currently, the supported options are:
  frequency = FREQUENCY
  ```
  -The supported values for `FREQUENCY` are 'always` and 'never', which control
  +The supported values for `FREQUENCY` are `always` and `never`, which control
  whether or not a message is printed out at the end of `cargo build` / `cargo check`.
  