Updating upgrading editions.md

[mdbiscan]

Updated the built-in components to use angle bracket syntax. See #692

[locks]

To make straight conversions, you need to prefix arguments with @, and then you need curlies on the right hand side, so something like <Input @value={{this.componentProperty}}.

[mdbiscan]

To make straight conversions, you need to prefix arguments with @, and then you need curlies on the right hand side, so something like <Input @value={{this.componentProperty}}.

I get that. I was taken aback on @value={{@value}}. Thanks for the protips!

[locks]

Thanks for the help!