docs: add docstring for method

Signed-off-by: Kamui <fin-kamui@pm.me>

Author: kamui-fin

tuf/api/metadata.py

@@ -1739,6 +1739,9 @@ def verify_length_and_hashes(self, data: Union[bytes, IO[bytes]]) -> None:
         self._verify_hashes(data, self.hashes)
 
     def get_prefixed_paths(self) -> List[str]:
+        """
+        Returns hash-prefixed paths for the given target file path.
+        """
         paths = []
         path = pathlib.Path(self.path)
         name, parent = path.name, path.parent