Sitecore.Feature.Metadata doesn't include serialized system settings

[JamesSkemp]

Describe the bug
The Metadata Feature module includes a field that points to an item path in Sitecore, /sitecore/system/Settings/Feature/Metadata

However, there is no such serialized path in the module's serialization directory

Sitecore Version
Sitecore 9.current

To Reproduce
Steps to reproduce the behavior:

1. Serialize Feature.Metadata items to Sitecore.
2. Add /sitecore/templates/Feature/Metadata/_PageMetadata as a base template on an item.
3. Scroll down to Meta Keywords field.
4. See that it points to /sitecore/content/home

Expected behavior
Feature.Metadata.Serialization.config should include /sitecore/system/Settings/Feature/Metadata in the configuration.

Additional context
Appears to be semi-related to #175.

Was probably switched to this more generic location and then never updated. Each site could override this, although Habitat seems to add the site-specific keywords under Metadata.