docs: update PR template to deprecate README and promote MCP Registry

Updated pull request template to inform contributors that adding servers to
the README is deprecated. Contributors should now publish servers to the MCP
Server Registry instead, following the quickstart guide.

Changes:
- Added "Publishing Your Server" section with deprecation notice
- Updated checklist to include MCP Registry publishing
- Clarified README item refers to server's own documentation

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

.github/pull_request_template.md

@@ -2,6 +2,12 @@
 
 ## Description
 
+## Publishing Your Server
+
+**Note: Adding servers to the README is now deprecated.** Instead, please publish your server to the [MCP Server Registry](https://github.com/modelcontextprotocol/registry) to make it discoverable to the MCP ecosystem.
+
+To publish your server, follow the [quickstart guide starting from the "Install MCP Publisher" step](https://github.com/modelcontextprotocol/registry/blob/main/docs/modelcontextprotocol-io/quickstart.mdx#step-3-install-mcp-publisher).
+
 ## Server Details
 <!-- If modifying an existing server, provide details -->
 - Server: <!-- e.g., filesystem, github -->
@@ -27,7 +33,8 @@
 <!-- Go over all the following points, and put an `x` in all the boxes that apply. -->
 - [ ] I have read the [MCP Protocol Documentation](https://modelcontextprotocol.io)
 - [ ] My changes follows MCP security best practices
-- [ ] I have updated the server's README accordingly
+- [ ] I have published my server to the MCP Server Registry (recommended for new servers)
+- [ ] I have updated the server's own README with documentation
 - [ ] I have tested this with an LLM client
 - [ ] My code follows the repository's style guidelines
 - [ ] New and existing tests pass locally