Improve error boundary docs

[amirhhashemi]

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• This PR references an issue (except for typos, broken links, or other minor problems)

Description(required)

This PR:

1. Clarifies when <ErrorBoundary> does and doesn't catch an error.

2. Improves the examples:

   1. The image on the Error boundary page doesn't illustrate the code beside it correctly. I think it's not needed here so I removed it. If you think it's necessary, a new image must be created which I think requires access to your Eraser account.
   2. The examples are often very minimal and don't show the whole picture. For instance:

   import { ErrorBoundary } from "solid-js";
   
   <ErrorBoundary fallback={(err) => <div>Error: {err.message}</div>}>
       <ProblematicComponent />
   </ErrorBoundary>

   I don't understand the reasoning behind this formatting but I think it's valuable for the examples to be complete to avoid potential confusion. Also, Prettier formats these incorrectly, and that could be a problem when we inforced formatting in CI.

   import { ErrorBoundary } from "solid-js";
   
   <ErrorBoundary fallback={(err) => <div>Error: {err.message}</div>}>
       <ProblematicComponent />
   </ErrorBoundary>;

   Notice the semicolon at the end.

3. Adds more information to the <ErrorBoundary> reference page.

4. Explains error boundaries more coherently.

Related issues & labels

• Closes [Content]: ErrorBoundary content is incorrect #586

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