Improve docs `Contributing to Pydantic` section

Documentation’s Contributing to Pydantic section says that basically once you’ve made your changes you run make format and then make. make invokes Makefile’s all rule that includes tests with coverage report, linting and mypy recipes. Although you are safe to not breaking style guides and tests locally, you still can:

1. Break rst files, so that sphinx will fail – you’ll find out once PR is open and Travis CI check is done (this is what I did in my very first PR)
2. Slow down pydantic with the changes made – you won’t find out without make benchmark-all (great performance mentioned as one of the pydantic’s advantages in Rationale section, so it’s important, isn’t it?)

I think there are a couple of ways to fix that:

1. Add new Makefile rule called full-check:

.PHONY: full-check
full-check: testcov lint mypy external-mypy docs benchmark-all

Then add a short note to contributing section about it.

1. Just add a note to contributing section to raise awareness about spinx build and performance check.

A small improvement to Benchmarks section could also be done. It probably should say that random module used in benchmarking gives non-deterministic results and also many other factors (e.g. other processes running by the OS when benchmarking) may also affect the benchmark results, so they probably should be taken with a grain of salt.

[samuelcolvin]

I don’t think make full-check is necessary, it’s not much faster than typing make && make docs.

I agree on benchmarking being a separate issue.

Regarding single quotes & blank, I have a modified version of black that enforces single quotes (actually it only takes a one line change). However given the acrimony over the original issue, I’m hesitant to release it. For now I think it’s fine just to document this.

[samuelcolvin]

yes please, that would be great.