Remove anchors in references to suggested attribute values from draft mets 2 schema

[aelkiss]

The schema documentation should link only to https://github.com/mets/METS-schema/wiki/METS2-Suggested-Attribute-Values, not to specific anchors. This gives flexability to reorganize that page in the future if need be.

[aelkiss]

This is still outstanding as of 2025-04-09. We should remove the anchors and release this as schema version 2.0.1, although it's not terribly urgent unless/until we want to reorganize https://github.com/mets/METS-schema/wiki/METS2-Suggested-Attribute-Values.