Contributing Guide - Helping our users resolve build failures.

[tomchristie]

Prompted by this comment: #153 (comment) (And a thousand and one other similar cases, where folks are getting stuck in and trying to help, but need some assistence indentifying the cause of a failing build.)

If we're feeling particularly proactive, we might want to try to help folks identify and understand build failures more clearly, eg including an example screenshot like this...

And explaining the "check" is code linting, the "docs" is the documentation build, and the others are tests against various python versions.

That way we could start to lead contributors down the happy path of being able to identify:

• Failures due to code linting.
• Failures due to test coverage <100%.
• Failures due to a test failure across all python versions.
• Failures due to a test failure on a specific python version.

I even think it'd be reasonable to visually walk folks through the PR process, and include pointers such as...

"Once you've submitted your pull request, the tests will automatically run, and the results will show up in GitHub. If the test suite fails, you'll want to click through to the "Details" link, and try to indentify why the tests failed."

A bit of visual handholding there would be a great step for introducing folks into the general workflow.