audio.experimental.a-lec.org: fix website build.

Without that fix we have the following with guix
65e8472a4b6fc6f66871ba0dad518b7d4c63595e ("system: Remove nss-certs
from OS templates, adjust doc."):
    building /gnu/store/qcf2709aq1nzh709fg2jvdq56diw75rd-website-0.1.drv...
    Backtrace:
    In guix/store.scm:
      1409:13 19 (map/accumulate-builds #<store-connection 256.100 7f15…> …)
      1384:11 18 (map/accumulate-builds #<store-connection 256.100 7f15…> …)
       1302:8 17 (call-with-build-handler #<procedure 7f15cec04f00 at g…> …)
      2182:25 16 (run-with-store #<store-connection 256.100 7f15d0fd8140> …)
    In guix/gexp.scm:
       1205:2 15 (_ _)
       1072:2 14 (_ _)
        913:4 13 (_ _)
    In guix/store.scm:
      2067:12 12 (_ #<store-connection 256.100 7f15d0fd8140>)
      1409:13 11 (map/accumulate-builds #<store-connection 256.100 7f15…> …)
      1384:11 10 (map/accumulate-builds #<store-connection 256.100 7f15…> …)
       1302:8  9 (call-with-build-handler #<procedure 7f15cec04ea0 at g…> …)
      2182:25  8 (run-with-store #<store-connection 256.100 7f15d0fd8140> …)
    In guix/gexp.scm:
       918:13  7 (_ _)
    In guix/store.scm:
       2010:8  6 (_ _)
    In guix/gexp.scm:
       299:22  5 (_ _)
    In guix/store.scm:
       2010:8  4 (_ _)
      2054:38  3 (_ #<store-connection 256.100 7f15d0fd8140>)
    In guix/grafts.scm:
        336:4  2 (graft-derivation _ _ _ #:guile _ #:outputs _ #:system _)
    In ice-9/boot-9.scm:
      1685:16  1 (raise-exception _ #:continuable? _)
      1685:16  0 (raise-exception _ #:continuable? _)

    ice-9/boot-9.scm:1685:16: In procedure raise-exception:
    Throw to key `match-error' with args `("match" "no matching pattern" ())'.
    install: missing destination file operand after 'mumble-vm.img'
    Try 'install --help' for more information.
    make: *** [Makefile:707: mumble-vm.img] Error 1

Signed-off-by: Denis 'GNUtoo' Carikli <GNUtoo@cyberdimension.org>

audio.experimental.a-lec.org/Makefile.am

@@ -89,6 +89,10 @@ mumble-vm.img: $(IMAGE_SOURCE)
 			--image-type=mbr-raw \
 			--image-size=6G mumble-vm-system.scm` \
 		$@
+build:
+	guix system build \
+		--image-type=mbr-raw \
+		--image-size=6G mumble-vm-system.scm
 
 mumble-vm.tar: $(TARBALL_SOURCE)
 	tar --exclude "id_ed25519" -cf $@ $(TARBALL_SOURCE)

audio.experimental.a-lec.org/mumble-vm-system.scm.tmpl

@@ -59,6 +59,7 @@
 needed for unattended upgrades to work.")
     (home-page "DOMAIN")
     (license license:gpl3+)))
+
 (define website
   (package
     (name "website")
@@ -69,8 +70,8 @@ needed for unattended upgrades to work.")
     (arguments
      (list
      #:install-plan
-     #~(list '("index.html" "var/www/DOMAIN/")
-             '(#$source  "var/www/DOMAIN/"))))
+     #~(list '("first-boot.sh" "var/www/DOMAIN/")
+             '(#$source "var/www/DOMAIN/mumble-vm.tar.xz"))))
     (synopsis "The DOMAIN website.")
     (description
      "The website contains how to use the service, and how to