Expose TUF metadata on files:9001

It exposes the TUF metadata at `http://files:9001:tuf-metadata` in the
container network.
For developers at `http://localhost:9001/tuf-metadata`.

This commit includes the entry on `docker-compose.yml` and the
`rstuf-metadata` volume which is attached to the `files` container.

Signed-off-by: Kairo Araujo <kairo.araujo@testifysec.com>

Author: Kairo Araujo

docker-compose.yml

@@ -135,6 +135,7 @@ services:
       - packages-archive:/var/opt/warehouse/packages-archive
       - sponsorlogos:/var/opt/warehouse/sponsorlogos
       - simple:/var/opt/warehouse/simple
+      - rstuf-metadata:/var/opt/warehouse/tuf-metadata
     ports:
       - "9001:9001"