Doc: add docs for Component Error example

Document the example.
Edit text in the example files.
Add a screenshot.

Change-Id: Ib5c3e0d78006d81ec77c75c92b7636f358e83412
Reviewed-by: Tim Jenssen <tim.jenssen@digia.com>
Reviewed-by: Kai Koehne <kai.koehne@digia.com>