Add a section to the README for icon generation

[jrjohnson]

Uses the ember-cli-image-transformer addon to convert a single image
into multiple needed icon sizes.

@san650 as we discussed in Slack here are some basic docs for using ember-cli-image-transformer to build icons for web apps. I wasn't too sure what should be included here so please let me know if I missed the mark.

[san650]

@jrjohnson as you can see, one of the original ideas of the addon was to tackle the image generation as one of the features, but I'm glad there's a different addon that do that work!

I like the documentation you added, I left some comments. Let me know your thoughts!

[san650]

I think the link is not correct, it should be #generatingicons

[san650]

I would add a paragraph above this one to make it clear that you have to install this other addon first.

ember-web-app doesn't generate icons or images. If you want to automate the generation of icons starting from a master image, you can install ember-cli-image-transformer.

What do you think? So people don't get the wrong idea that this addon installs ember-cli-image-transformer.

[jrjohnson]

I agree, that will be a lot clearer.

[san650]

Just an idea here, maybe we can use the same size array that you use in the other config. I like to give users ideas on how to make the config a bit more DRY 😄

// config/manifest.js
export default function() {
  return {
    icons: [192, 512].map((size) => ({
      src: `/images/icons/android-chrome-${size}.png`,
      sizes: `${size}`,
      type: "image/png"
    }))
  };
}

[jrjohnson]

Thanks for this especially. I'm 100% going to steal it to improve our manifest.js!

[jrjohnson]

Thanks for the quick feedback @san650. Those all looks like great additions. I will try and get them done in the next 24 hours.

[jrjohnson]

I ended up having some time tonight, so these changes are made now.

[san650]

Thanks for contributing!