Add benchmarks to our docs

[b5]

@WildBlueGuy has done a great set of validator comparison benchmarks: https://github.com/WildBlueGuy/validator-benchmarks

We should add benchmarks to our README.md that run just our version of that test suite so others can get a sense of the time it takes to validate a document.

Steps to Complete

• fork this repo
• pull the BenchmarkQri test from the wild blue's repo into a file called benchmark_test.go
• add a commit using our commit guidelines. something like: test(benchmarks): incorporate benchmark test from WildBlueGuy validator comparison
• execute the tests on your machine: go test --bench=. -v --run=XXX -benchmem
• add the output to stats adding a shoutout to the validator-benchmarks repo for comparison
• commit the readme changes, using some message like: docs(readme): add benchmarks to readme
• file a PR!

[ghost]

Hey that's me! Glad y'all are finding these useful. They got merged onto https://json-schema.org/implementations.html finally!