Add metadata output

Signed-off-by: CrazyMax <crazy-max@users.noreply.github.com>

action.yml

@@ -36,6 +36,10 @@ inputs:
     description: "List of targets values to override (eg. targetpattern.key=value)"
     required: false
 
+outputs:
+  metadata:
+    description: 'Build result metadata'
+
 runs:
   using: 'node12'
   main: 'dist/index.js'