Update wording

wiki/src/contribute/working_together/roles/foundations_team.mdwn

@@ -14,7 +14,7 @@ The Tails Foundations Team is responsible for:
   - keeping our core code base up-to-date and maintainable, e.g.
     refactor or clean up stuff that has bit-rotted, migrate code that
     would otherwise rely on obsolete technologies;
-  - maintaining the ISO build system;
+  - maintaining the Tails ISO and USB images build system;
   - doing the _extra_ peer-review and
     [[release management|release manager]] work that corresponds to
     the above bullet points;