Help: UNKNOWN_LIBRARY is a valid file API target type

This was missed in the change that added imported targets to the
file API replies, b626843d71 (fileAPI: Output all INTERFACE and
IMPORTED targets, 2025-09-13). The release notes and file API schema
did get the update to mention it, only the description of the `type`
field in the file API docs was missed.
1 file changed