Add `stdbool` include to `file_disemvowel` skeleton
Add `stdbool` include to `file_disemvowel` skeleton

Since the "type" `bool` is referenced in the skeleton, it seemed sensible to add this include so that the skeleton would actually compile.

UMM-CSci-Systems/Traversing-Directories-starter,UMM-CSci-Systems/Traversing-Directories-starter