URLs in schema documentation are relative to menuinst docs

[marcoesters]

Checklist

• I added a descriptive title
• I searched open reports and couldn't find a duplicate

What happened?

The links in the schema documentation point to a relative path in the menuinst documentation, even though they should lead to external sites.

For example, the URL in the entitlements field should point to https://developer.apple.com/documentation/bundleresources/entitlements, but instead points to https://conda.github.io/menuinst/reference/entitlements

Additional Context

No response

[jaimergp]

Opened #190