Document anti-pattrens regarding props

[hamza1311]

I think we should document anti-patterns. I would be fine with making a PR for those but first we need to list them.

1. Taking String, instead of Cow<'static, str> as props.
2. What else?

From #1834 (comment), as requested by @siku2

[martinitus]

For a beginner (like me) who also doesn't have any significant frontend / react experience some more general "dos & and don'ts" would also be really helpful. Questions I am uncertain about include stuff like:

• How much data should/could I pack into props: like 10000 structures that get rendered as a list/child elements?
• How do I enable a component to fetch data (e.g. via an agent)? Should the handle to the agent be part of the props or of the struct?
• When should I put stuff into the props, and which kind of objects should I maintain in the actual component struct?
  Hth

[hamza1311]

A section about anti-patterns/what not to do on the Properties page would be enough.