[docs] updates all docs to use Angle Bracket syntax

[gabrielcsapo]

Motivation

I have been using this library to refactor a project I am working on (gabrielcsapo/broccoli-inspector#22) and it has been an awesome help! I am currently trying to use all the octane features and ensure that we are using angle brackets. Having the docs updated to use angle brackets helps for quickly prototyping stuff out!

Example

Here is just an excerpt of how the button pages looks with the codemod run.

checks off angle brackets from #1117

[miguelcobain]

@gabrielcsapo thank you so much. This definitely makes us not look so outdated. 👍