Add "Pringles" style note for using Rule keyword in Gherkin

[luke-hill]

Once you pop you just can't stop.

When using a Rule keyword in Gherkin, you cannot then "un-use" it, i.e. the following is not semantically possible (Nor will it ever likely be).

Feature: A
  Background:
    Given whatever
  Rule: One
    # many scenarios
  Rule: Two
    # many scenarios
  Scenario: Standalone Scenario

A User should either make the Standalone scenario part of a new Rule and call it Rule: Other stuff or alternatively alter the structure of their gherkin document like so

Feature: A
  Background:
    Given whatever
  Scenario: Standalone Scenario
  Rule: One
    # many scenarios
  Rule: Two
    # many scenarios

[aslakhellesoy]

What are you suggesting here @luke-hill ?

[luke-hill]

Updating the docs stating "how" Rules should be used and how you should structure your feature files. To avoid this scenario where you can't "un-use" a rule.

[mattwynne]

Go for it Luke! Do you want some feedback on your intended changes to the copy?

[luke-hill]

I'll pop a PR in first, and tag you and some of the others. So long as we're happy with my analogy. Also I know we try to steer clear of "This is correct", and just say "This is incorrect", but in this instance I really think my 2 options are the "only" correct ones.