Fix examples for channel form `field_errors` tag

[intoeetive]

Overview

Replace this paragraph with a description of your changes and reasoning. Provide links to external references/discussions if appropriate.

Resolves #NN.

Nature of This Change

• [ ] 🐛 Fixes a bug
• [ ] 🚀 Implements a new feature
• [ ] 🛁 Rewrites existing documentation
• [ ] 💅 Fixes coding style
• [ ] 🔥 Removes unused files / code

Related Application Change

Application Pull Request: https://github.com/ExpressionEngine/ExpressionEngine/pulls/NNN