Discord link goes to landing page instead of directly joining - can we use a direct invite?

## Description

The Discord link in README (`https://docling.ai/discord`) goes through a blank landing page before redirecting to the actual Discord invite. This creates a confusing experience for new users trying to join the community.

### Current flow:
1. Click Discord badge → redirected to `www.docling.ai/discord`
2. Blank page loads briefly
3. Then redirects again to the actual Discord invite

### Suggested improvement:

Replace with a direct `discord.gg/xxxxx` invite link so users can join in one click.

**Benefits:**
- Simpler onboarding for new users
- Better mobile experience (opens Discord app directly)

Could you share the direct Discord invite link? Happy to help with a PR if needed.

Thanks!