docs: retire third-party server list in favor of MCP Registry

The Third-Party Servers section (Official Integrations + Community
Servers) has been superseded by the MCP Registry at
https://registry.modelcontextprotocol.io/. The README already carried a
deprecation note and CONTRIBUTING.md froze new additions. This removes
the list, updates CONTRIBUTING.md to describe the new state, and
refreshes the readme-pr-check workflow's bot comment.

.github/workflows/readme-pr-check.yml

@@ -46,7 +46,7 @@ jobs:
               body: [
                 'Thanks for your contribution!',
                 '',
-                '**We are no longer accepting PRs to add new servers to the README.** The server lists are deprecated and will eventually be removed entirely, replaced by the registry.',
+                '**We are no longer accepting PRs to add new servers to the README.** The third-party server list has been removed from this README in favor of the [MCP Server Registry](https://registry.modelcontextprotocol.io/).',
                 '',
                 '👉 **To add a new MCP server:** Please publish it to the [MCP Server Registry](https://github.com/modelcontextprotocol/registry) instead. You can browse published servers at [registry.modelcontextprotocol.io](https://registry.modelcontextprotocol.io/).',
                 '',

CONTRIBUTING.md

@@ -6,9 +6,9 @@ We accept changes through [the standard GitHub flow model](https://docs.github.c
 
 ## Server Listings
 
-We are **no longer accepting PRs** to add server links to the README. Please publish your server to the [MCP Server Registry](https://github.com/modelcontextprotocol/registry) instead. Follow the [quickstart guide](https://github.com/modelcontextprotocol/registry/blob/main/docs/modelcontextprotocol-io/quickstart.mdx).
+The README no longer contains a list of third-party MCP servers — that list has been retired in favor of the [MCP Server Registry](https://github.com/modelcontextprotocol/registry). To make your server discoverable, follow the [quickstart guide](https://github.com/modelcontextprotocol/registry/blob/main/docs/modelcontextprotocol-io/quickstart.mdx) to publish it there.
 
-You can browse published servers using the simple UI at [https://registry.modelcontextprotocol.io/](https://registry.modelcontextprotocol.io/).
+You can browse published servers at [https://registry.modelcontextprotocol.io/](https://registry.modelcontextprotocol.io/).
 
 ## Server Implementations