[Feat]: Provide a BlogPosts section for community posts

### Is your feature request related to a problem? Please describe.

Currently, the A2A community lacks a centralized, official space to share their success stories, learnings, and technical implementations.

While users are building great things with A2A—such as new extensions, custom applications, and organizing events—this knowledge is scattered or lost. We need a dedicated avenue to highlight community contributions and educational content.

### Describe the solution you'd like

I propose creating a dedicated space for community-driven content. This could either be a dedicated community folder within the main A2A repository's documentation, or a separate sub-repository (e.g., a2aproject/a2a-community).

This space would host Markdown-based articles covering:

- Educational content: Tutorials and learnings about A2A.
- Success Stories: Case studies (e.g., "How ACME used A2A to...").
- Ecosystem updates: Showcasing new extensions and applications.
- Community Events: Recaps and announcements for hackathons, online meetups, and in-person events (e.g., "A2A Hackathon in London").

Proposed Directory Structure Example:
```
community/
|-- blog-posts/
| |-- how-acme-used-a2a-helped.md
| |-- a2a-hackathon-in-london.md
|-- events/
|-- guidelines.md
```

### Describe alternatives you've considered

- Reddit / GitHub Discussions: While excellent for Q&A and general chats, it doesn't offer the structured, article-style readability and discoverability of dedicated documentation or a blog format.

- External platforms (Medium, Dev.to, etc.): Having users post independently fragments the community and makes it harder for new users to find a centralized hub of authoritative A2A community knowledge.

### Additional context

Providing a standardized Markdown template for these submissions (e.g., a blog-post-template.md) would significantly lower the barrier to entry and encourage more community members to share their work

```
blog
|-----
|----- /index.md
```

### Code of Conduct

- [x] I agree to follow this project's Code of Conduct