docs: add README for every content directory

Each directory (agents, hands, integrations, plugins, providers,
scripts, skills) now has a README documenting its TOML format,
current contents, and contribution steps.

integrations/README.md

@@ -0,0 +1,70 @@
+# Integrations
+
+MCP (Model Context Protocol) server integration templates for LibreFang. Each integration connects LibreFang to an external service (GitHub, Slack, databases, etc.).
+
+## Structure
+
+```
+integrations/
+├── github.toml
+├── slack.toml
+├── postgresql.toml
+└── ...
+```
+
+## Integration TOML Format
+
+```toml
+id = "service-id"                 # Must match filename (without .toml)
+name = "Service Name"
+description = "What this integration provides"
+category = "devtools"             # devtools | communication | storage | monitoring | data
+icon = "🐙"
+tags = ["relevant", "tags"]
+
+[transport]                       # MCP server transport config
+type = "stdio"                    # "stdio" or "sse"
+command = "npx"
+args = ["-y", "@pkg/mcp-server"]
+
+[[required_env]]                  # Required environment variables
+name = "SERVICE_API_KEY"
+label = "API Key"
+help = "How to obtain this key"
+is_secret = true
+get_url = "https://..."
+
+[oauth]                           # Optional: OAuth config
+provider = "github"
+scopes = ["repo"]
+auth_url = "https://..."
+token_url = "https://..."
+
+[health_check]
+interval_secs = 60
+unhealthy_threshold = 3
+
+setup_instructions = """
+Step-by-step setup guide for users.
+"""
+```
+
+## Current Integrations (25)
+
+| Integration | Category | Service |
+|-------------|----------|---------|
+| github | devtools | GitHub repos, issues, PRs |
+| slack | communication | Slack messaging |
+| notion | productivity | Notion pages and databases |
+| postgresql | storage | PostgreSQL database |
+| ... | | See each file for details |
+
+## Adding a New Integration
+
+1. Create `integrations/<name>.toml`
+2. Ensure `id` matches the filename
+3. Test the MCP server command locally
+4. Run `python scripts/validate.py`
+5. Submit a PR
+
+See [CONTRIBUTING.md](../CONTRIBUTING.md) for the full guide.