--generate-dir option to publish heroku, refs #1905

docs/cli-reference.rst

@@ -501,6 +501,8 @@ See :ref:`publish_heroku`.
       -n, --name TEXT                 Application name to use when deploying
       --tar TEXT                      --tar option to pass to Heroku, e.g.
                                       --tar=/usr/local/bin/gtar
+      --generate-dir DIRECTORY        Output generated application files and stop
+                                      without deploying
       --help                          Show this message and exit.
 
 

docs/publish.rst

@@ -73,6 +73,10 @@ This will output some details about the new deployment, including a URL like thi
 
 You can specify a custom app name by passing ``-n my-app-name`` to the publish command. This will also allow you to overwrite an existing app.
 
+Rather than deploying directly you can use the ``--generate-dir`` option to output the files that would be deployed to a directory::
+
+    datasette publish heroku mydatabase.db --generate-dir=/tmp/deploy-this-to-heroku
+
 See :ref:`cli_help_publish_heroku___help` for the full list of options for this command.
 
 .. _publish_vercel: