Compose Multi-platform tutorial

[shannah]

With platform-specific bundles, the Compose Multi-platform support is now pretty good. Demo https://github.com/shannah/jdeploy-people-in-space.

To do:

1. Update the "Import project" function to generate .jdpignore and platform-specfic configuration in package.json if compose multi-platform is detected.
2. Create a screencast showing how to setup a Compose multi-platform project
3. Create a companion tutorial for Compose multi-platform
4. Create project template for compose multi-platform project