build(licensure): Add c headers to known files

.licensure.yml

@@ -111,6 +111,7 @@ comments:
       - css
       - cpp
       - c
+      - h
     # This demonstrates a block commenter configuration. A block
     # commenter type will add start_block_char as the first character
     # in the license header and add end_block_char as the last character