Update documentation for Order#getAppliedRuleIds

[zack6849]

Description

Update the documentation for getAppliedRuleIds, as it is not immediately clear if this is a single number in a string, or several that are comma separated.

Manual testing scenarios

• Attempt to getAppliedRuleIds on an OrderInterface object
• Consult the documentation, and see it contains a string
• Scratch your head because you're not sure if it can contain multiple IDs or not, and if so how they're separated

Contribution checklist

• Pull request has a meaningful description of its purpose
• All commits are accompanied by meaningful commit messages
• All new or changed code is covered with unit/integration tests (if applicable)
• All automated tests passed successfully (all builds on Travis CI are green)

[magento-engcom-team]

Hi @zack6849. Thank you for your contribution
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[rodrigowebjump]

Hi, you include an empty line before long description, but removed the line after.

Please, include the empty line after long description :-)

Refer: https://devdocs.magento.com/guides/v2.3/coding-standards/docblock-standard-general.html

[rodrigowebjump]

Hi @zack6849 Thanks for your contribution

[magento-engcom-team]

Hi @rodrigowebjump, thank you for the review.
ENGCOM-3199 has been created to process this Pull Request

[okorshenko]

merged

[magento-engcom-team]

Hi @zack6849. Thank you for your contribution.
We will aim to release these changes as part of 2.3.1.
Please check the release notes for final confirmation.