chore: move ignore_classes in docs

[brnhensley]

Overview

Moving the error_collector.ignore_classes config details so the error_collector section is alphabetized as this is the only section out of place. This also groups the ignore_ section in a logical way for browsing the config doc.

Submitter Checklist:

• Include a link to the related GitHub issue, if applicable
• Include a security review link, if applicable

Testing

The agent includes a suite of unit and functional tests which should be used to
verify your changes don't break existing functionality. These tests will run with
GitHub Actions when a pull request is made. More details on running the tests locally can be found
here for our unit tests,
and here for our functional tests.
For most contributions it is strongly recommended to add additional tests which
exercise your changes.

Reviewer Checklist

• Perform code review
• Add performance label
• Perform appropriate level of performance testing
• Confirm all checks passed
• Add version label prior to acceptance

[hannahramadan]

Thank you!