Add context regarding Harper caching

[kylebernhardy]

Caching is critical component in Harper's ability to provide superior performance when coupled with other areas like API acceleration, next.js apps, etc...

I have created an app prompting to create a weather API project that uses Open Weather API as the origin and cache the response. The TTL would adhere to the Cache-Control from the response and default to a 15 minute expiration. The generated app did not set a default expiration on the table, not did it setup a sourcedFrom. The Resource code also did not apply the expiration properly at the record level.

Adding context regarding Harper's native caching will add better fidelity in the generated app as well as create better interactivity with Agent.