Tor Browser import process: clean up after ourselves.

wiki/src/contribute/release_process/tor-browser.mdwn

@@ -227,3 +227,10 @@ Adjust the URL in the main Git repository
        git commit config/chroot_local-includes/usr/share/tails/tbb-dist-url.txt \
            -m "Fetch Tor Browser from our own archive."
     done
+
+Clean up
+--------
+
+	cd "$TBB_ARCHIVE" && \
+	git annex drop -- "${TBB_VERSION}" && \
+    rm -rf "$DL_DIR"