[add] platforms (Issue #27)

[rhyannonjoy]

• Resolves Issue [add] platforms, remove KPL #27
• Create Platforms page, adapted from AET Platform Comparisons
• Removed Known Platform Limits table, reference to it in README.md with links to Platforms page

Questions:

1. I added platforms.md to site/content is that the right spot?
2. I thought about a version bump, but considering this is a content addition and not a change to the main spec categories, maybe it doesn’t need one?

[dacharyc]

Awesome - thank you so much for adding this, @rhyannonjoy ! I'm going to merge and then make a few tweaks with the Hugo setup stuff before deploying. I'll ping you when it's live!

So incredibly appreciative of all your work researching and populating this information for us 🎉 💖