Add download button to app icons

[winslet]

Summary

We should be able to download the app icons for IBM products within the design language site without rooting through the design language github repo.

Justification

Why: I find we need to point our and other Development teams and PM teams to our app icon quite a lot - considering this repo is the 'single source of truth' it would be great to have the ability to download the app icons directly from the library, like we can on the carbon icons and the other icon pages within the design language site.

Desired UX and success metrics

On the Carbon Icons page we have a download available:

---

On the UI icons page within the design language site we have a download available:

---

So its strange/annoying that we do not have the download functionality available on the app icons page - one that would be really really useful to have.

"Must have" functionality

The ability to quickly access and download product icons for IBM products.

Specific timeline issues / requests

No, but its painful every time I have to go dig through the app icons repo to get there, so as quickly as makes sense.

Available extra resources

What resources do you have to assist this effort?

Link to where the icons live: https://github.com/carbon-design-system/design-language-website/tree/master/src/images/app-icons

Carbon is a collaborative system. We encourage teams to build components and submit them for integration as either add-ons or core components.

[mjabbink]

@winslet We avoided this a bit to prevent the ease of download since these are related to products and service and less “open source” if you will. They are all available as downloads on the Design tab