Edit note in section 4.5 to add 'any'. Change requested by reviewer (seb)

Signed-off-by: Vladimir Diaz <[email protected]>

Author: vladimir-v-diaz

tuf-spec.md

@@ -1164,7 +1164,7 @@ non-volatile storage as FILENAME.EXT.
 
   * **4.5**. **Perform a preorder depth-first search for metadata about the
   desired target, beginning with the top-level targets role.**  Note: If
-  metadata requested in steps 4.5.1 - 4.5.2.3 cannot be downloaded nor
+  any metadata requested in steps 4.5.1 - 4.5.2.3 cannot be downloaded nor
   validated, end the search and report that the target cannot be found.
 
     * **4.5.1**. If this role has been visited before, then skip this role (so