docs: update docs and readme

docs/en/skills/hub.mdx

@@ -0,0 +1,65 @@
+---
+title: Skill Hub
+description: Browse, search, and install AI Agent skills
+---
+
+[Cow Skill Hub](https://skills.cowagent.ai/) is an open-source skill marketplace for AI Agents, aggregating official picks, community contributions, and third-party skills from GitHub, ClawHub, and beyond.
+
+Source code: [github.com/zhayujie/cow-skill-hub](https://github.com/zhayujie/cow-skill-hub)
+
+<img src="https://cdn.link-ai.tech/doc/20260401110103.png" width="800" />
+
+## Features
+
+- **Browse skills** — filter by category (Featured / Community / Third-party) and tags
+- **Search skills** — find skills by name or description
+- **View details** — read the skill manifest, file contents, install command, and required environment variables
+- **One-click install** — copy the install command and run it in CowAgent
+
+## Installing a skill
+
+Run the install command in chat or in your terminal:
+
+<CodeGroup>
+```text Chat
+/skill install <name>
+```
+
+```bash Terminal
+cow skill install <name>
+```
+</CodeGroup>
+
+You can also browse the marketplace directly from chat:
+
+```text
+/skill list --remote
+/skill search <keyword>
+```
+
+Beyond the curated list, you can install third-party skills from **GitHub, ClawHub, LinkAI, or any URL** via the CLI. See [Installing skills](/en/skills/install) for details.
+
+## Contributing a skill
+
+To submit your own skill:
+
+1. Visit [skills.cowagent.ai/submit](https://skills.cowagent.ai/submit)
+2. Sign in with GitHub or Google
+3. Upload a folder or zip file containing `SKILL.md`
+4. Skill name, display name, and description are auto-detected — adjust as needed
+5. Submit for review; skills go live after security and quality checks
+
+<img src="https://cdn.link-ai.tech/doc/20260401111904.png" width="800" />
+
+Skill file layout:
+
+```
+your-skill/
+├── SKILL.md        # required, in the root
+├── scripts/        # optional, runtime scripts
+└── resources/      # optional, additional assets
+```
+
+<Tip>
+  Skills are built around the `SKILL.md` manifest. You can also download `SKILL.md` from a skill's detail page and use it with any Agent that supports custom instructions (OpenClaw, Cursor, Claude Code, and more).
+</Tip>