CHANGELOG update for cucumber/cucumber #251

[mxygem]

Summary

Lots of changes in accordance with cucumber/cucumber 251

Motivation and Context

Working to normalize documents across the various repos.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Refactoring (cleanup of code base without changing any existing functionality)
• Update documentation

Checklist:

• I've added tests for my code
• My change requires a change to the documentation.
• I have updated the documentation accordingly.

[mxygem]

Documentation only changes, does not impact code-base so test success/failure is not indicative of my changes. Merging!

[mxygem]

Hey! So, as a heads up, I got a bit eager in making some doc updates and moved forward without being fully aware of various processes. With that said, if my merging and deleting branches too soon has caused issues and you'd like me to fix or flat out revert this PR, happy to do so as I definitely don't want to cause issues/step on toes. If you have a preferred fix method you'd like me to run, please send it my way.

Thanks and sorry if this has caused any troubles!

Check out the #committers channel in Slack for more.