feat: add llms.txt for AI tool discoverability and documentation access

Feature: Add llms.txt for AI tool discoverability

Description

Add an llms.txt file at the repository root (served at https://dokploy.com/llms.txt or https://docs.dokploy.com/llms.txt) following the llms.txt standard. This is a machine-readable markdown file that helps AI coding assistants (Cursor, Copilot, Claude Code, Gemini, etc.) discover and reference official documentation.

Why this matters for Dokploy

1. AI-native discoverability — AI tools automatically fetch llms.txt when a user asks about a project. Without it, they rely on web search (outdated/stale results) or training data (hallucination risk). With it, users get accurate, current answers from Dokploy's own docs.

2. Reduced support burden — Common questions ("How do I install on a VPS?", "How do I set up Cloudflare domains?", "How do I configure PostgreSQL backups?") get answered correctly by AI tools using primary-source docs instead of forum posts or guesses.

3. Ecosystem growth — AI tools recommend deployment solutions contextually. When llms.txt exists, Dokploy appears as a vetted, documented option in AI-generated comparisons and recommendations.

4. Low maintenance — A single markdown file with categorized links to existing docs. Updates only when new doc sections are added.

References

• llms.txt specification
• Projects that already use it: Docker, Framer, Mux, Vue.js, Supabase, n8n

Start by reviewing the repository's existing documentation structure and the llms.txt specification linked in the issue. Create the requested llms.txt at the repository root with categorized links to Dokploy's official documentation, then verify that it is served at the documented repository or docs URL.