docs/CLI: README documents `tool-search` subcommand that does not exist in the binary

[CAOShurong]

Problem

The README's "CLI utilities" section documents a tool-search subcommand:

github-mcp-server tool-search "<query>" searches tools by name, description, and input parameter names. Use --max-results to return more matches.
docker run -it --rm ghcr.io/github/github-mcp-server tool-search "issue" --max-results 5
github-mcp-server tool-search "issue" --max-results 5

But the shipped binary does not have this subcommand.

Reproduction

Installed the latest release and ran the documented command:

$ go install github.com/github/github-mcp-server/cmd/github-mcp-server@latest
$ github-mcp-server tool-search "issue" --max-results 5
Error: unknown command "tool-search" for "github-mcp-server"
Run 'github-mcp-server --help' for usage.

--help lists only completion, generate-docs, http, list-scopes, stdio. The same failure occurs with go run ./cmd/github-mcp-server tool-search ... on current main.

Root cause (git archaeology)

#1839 ("Add tool search CLI", released in v0.29.0) added:

• pkg/tooldiscovery/search.go + search_test.go (the search implementation)
• the README section advertising the CLI command

but the cobra subcommand itself was never registered in cmd/github-mcp-server/main.go — that PR's only main.go change removes a blank line. Since then, tooldiscovery.SearchTools has had zero callers outside its own package at every tag I checked (v0.29.0 through v1.11.0 and current main).

Suggested options

1. Implement the missing subcommand: register a tool-search command in cmd/github-mcp-server/main.go that builds the enabled-tool inventory and delegates to pkg/tooldiscovery.SearchTools (the package already implements scoring, --max-results, etc.). This makes the documented behavior true.
2. Or, if the CLI surface is intentionally deferred, remove/park the README section (and the Docker example) until it ships, so users don't hit unknown command.

Happy to put up a PR for option 1 if maintainers want the subcommand.