Reference the interruptible setting in "Auto-cancel pending pipelines"

What does this MR do?

This merge request improves the documentation for the automatic cancellation of pipelines. Jobs will not be cancelled if the interruptible parameter is not set to true.

While this behavior is documented in the documentation for the interruptible parameter, the documentation for the automatic cancellation of pipelines currently lacks this information.

Screenshots

none

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry not necessary
• Documentation (if required)
• Code review guidelines no code changed
• Merge request performance guidelines irrelevant
• Style guides
• Database guides not necessary
• Separation of EE specific content not necessary

Availability and Testing

Not needed. No code was changed.

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done