docs(skill): use new capability path in crypto example (#54)

## Summary

`agentkey_crypto` now dispatches by capability path (`market/quotes`,
`token/price`, …) instead of provider-prefixed type names (`cmc_quotes`,
`token_price`, …) after the server-side providerless rename. The
quickstart snippet in `SKILL.md` still showed the old `cmc_quotes`
example, which would 400 against the new server.

This PR updates that one example and switches it to the canonical
**nested params** envelope, which is the shape the catalog renders and
the shape the server forwards verbatim to upstreams.

```diff
- execute_tool(name="agentkey_crypto", params={type: "cmc_quotes", symbol: "BTC"})
+ execute_tool(name="agentkey_crypto", params={type: "market/quotes", params: {symbol: "BTC"}})
```

Pairs with chainbase-labs/AgentKey-Server#40 (the server rename). No
version bump needed — `docs:` prefix keeps release-please from cutting a
release.

Full migration table for callers:
`AgentKey-Server/docs/crypto-providerless-taxonomy.md`.

## Test plan

- [x] Snippet renders correctly in `SKILL.md`
- [ ] Verify against staging server after server PR merges

skills/agentkey/SKILL.md

@@ -280,7 +280,7 @@ execute_tool(name="agentkey_scrape", params={url: "https://example.com"})
 
 **Crypto prices:**
 ```
-execute_tool(name="agentkey_crypto", params={type: "cmc_quotes", symbol: "BTC"})
+execute_tool(name="agentkey_crypto", params={type: "market/quotes", params: {symbol: "BTC"}})
 ```
 
 For social/crypto with many endpoints, always discover first: