Revert "97312dd" and "d97da38"

This reverts commits:
- Clarify timestamp.json METAFILES format
97312dd

- LENGTH isn't optional in timestamp.json for snapshot.json
d97da38

Author: Lukas Puehringer

tuf-spec.md

@@ -979,31 +979,10 @@ repo](https://github.com/theupdateframework/specification/issues).
          "meta" : METAFILES
        }
 
-   METAFILES is an object whose format is the following:
-
-       { METAPATH : {
-             "version" : VERSION,
-             "length" : LENGTH, |
-             "hashes" : HASHES }
-         , ...
-       }
-
-   METAPATH is the snapshot.json file's path on the repository relative to the
-   metadata base URL.
-
-   VERSION is the version of the snapshot metadata as listed in the
+   METAFILES is the same is described for the snapshot.json file.  In the case
+   of the timestamp.json file, this MUST only include a description of the
    snapshot.json file.
 
-   LENGTH is the integer length in bytes of the snapshot metadata file.
-
-   HASHES is the dictionary that specifies one or more hashes of the snapshot
-   metadata file, including the cryptographic hash function.  For example:
-   { "sha256": HASH, ... }.
-
-   Note: METAFILES is the same as is described for the snapshot.json file, only
-   the LENGTH and HASHES are not optional and in the case of the timestamp.json
-   file, this MUST only include a description of the snapshot.json file.
-
    A signed timestamp.json example file:
 
        {