Update tuf/api/metadata.py (WIP)

Co-authored-by: Joshua Lock <[email protected]>

Author: lukpueh

tuf/api/metadata.py

@@ -275,7 +275,7 @@ def verify(self, key: JsonDict) -> bool:
 class Signed:
     """A base class for the signed part of TUF metadata.
 
-    Objects with base class Signed are usually included in a Metablock object
+    Objects with base class Signed are usually included in a Metadata object
     on the signed attribute. This class provides attributes and methods that
     are common for all TUF metadata types (roles).