Add examples about why writing to a signal during rendering is an issue to the warning message

Add a section about the `Writing to signals during a render error`
Especially with examples of what happens when filling out forms. It is not clear in which cases the render event occurs and why it can lead to an infinite loop. Examples in the console are not sufficient for a clear understanding of the error.

Locate the warning message titled “Writing to signals during a render error” and review its existing console examples. Add clear explanation of when rendering occurs, why writing during rendering can cause an infinite loop, and examples involving form filling; the warning should answer those questions without relying on the console output alone.

Written by the indexing model from the issue text.