Returns a list of the kinds of the subparts of assembly.
This is a list of instances of subpart-kind.
| subpart-kinds < basic-doclisp-part > |
| subpart-kinds < doclisp-asdf-system > |
| subpart-kinds :around < doclisp-assembly > |
| subpart-kinds < doclisp-class > |
| subpart-kinds < doclisp-condition > |
| subpart-kinds < doclisp-package > |