Add instructions and best practices to the README for dependent props

[tgolen]

Coming from this slack convo: https://expensify.slack.com/archives/C01GTK53T8Q/p1694710295343199

cc @mountiny @marcaaron @allroundexperts

[mountiny]

Looks good to me, thank you!

[parasharrajat]

What I used was two WithOnyx subsriptions. like

export default withOnyx({
    report: {
        key: ({reportID) => `${ONYXKEYS.COLLECTION.REPORT}${reportID}`,
    }})
withOnyx({
    policy: {
        key: ({report}) => `${ONYXKEYS.COLLECTION.POLICY}${report.policyID}`,
    },
})(App);

Is this different from single WithOnyx anyhow?

[tgolen]

@parasharrajat It functionally results in the same end result, but with two withOnyx() you've now double-wrapped the component which is inefficient and doesn't allow batch rendering to work as well (it's just add more things to the rendering tree). The same thing can be done with a single withOnyx() and it works.

[parasharrajat]

Glad to know. Thanks for the explanation.

[tgolen]

@mountiny @hayata-suenaga do one of you want to go ahead and merge this?