Add a complete working usage example to the documentation

[bjmc]

Hello, I'm new to Rust/Pest and I'm struggling a bit trying to figure out how to use this crate. I copy-pasted the example from the README and I'm getting a syntax error when running cargo test:

error: expected one of `(` or `<`, found `->`
  --> src/main.rs:24:21
   |
24 |   fn test_my_parser -> Result<(), Error> {
   |                     ^^ expected one of `(` or `<`

Do you have any minimal complete examples that show how to use pest-test to generate test cases to verify a pest PEG grammar? Thanks!

[jdidion]

Sorry you're having trouble getting it to work. Here is a repository that uses pest-test https://github.com/jdidion/pest-wdl. If you come up with a good minimal example, please submit a PR. Thanks!