docs: update type-enum default value

[khsily]

Description

A small change to update default value of type-enum based on config-conventional document

Motivation and Context

Usage examples

// commitlint.config.js
module.exports = {};

echo "your commit message here" | commitlint # fails/passes

How Has This Been Tested?

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.

[escapedcat]

Thanks!