Document lifecycle hooks

[ef4]

See "TODO. Document the lifecycle hooks and rationalize their names" in draft RFC.

[chadhietala]

I feel like we should part ways with all of the attrs hooks in general. I believe they were trying to chase the React model, however I believe have been detrimental in not only the mental model, but also performance. @krisselden likely has more specifics of the costs.

[ef4]

Some notes on the existing hooks are here https://docs.google.com/spreadsheets/d/11qvIJpchsbOr-1AdFSCAUmcC-0iTEWjjTwo6TGuDOEU/edit#gid=0