Add website callout to drive contributors to fix reported question issues

## Problem

Community members report question content bugs via GitHub issues (typically titled `[cert] Issue with `), but there is no visibility on the website itself to attract contributors to help fix them. These reports sit in the issue tracker with no consistent labeling and no way for website visitors to discover them.

## Proposed Solution

### 1. Create a `question-report` label
Create a dedicated `question-report` label to consistently tag all community-reported question issues. This enables reliable filtering and linking from the website.

Apply this label to all existing and future "Issue with" question reports.

### 2. Add a callout on the landing page
Add a visible callout on the website (suggested placement: near the contributors section on the landing page) that:

- Communicates that the project needs help reviewing and fixing reported question issues
- Links directly to the GitHub issues tab filtered by the `question-report` label:
`https://github.com/FidelusAleksander/ghcertified/issues?q=is:issue+is:open+label:question-report`
- Fits naturally with the existing community/contribution messaging on the landing page

### Why this matters
- **Lowers the barrier** for new contributors — they can find actionable, scoped work immediately
- **Improves question quality faster** — more eyes on reported issues means quicker fixes
- **Strengthens community engagement** — website visitors see that contributions are welcomed and needed