refactor: Move SDK to New Repository (#518)

Python SDK codebase is now in https://github.com/google/a2a-python

Author: holtskinner

.github/actions/spelling/allow.txt

@@ -10,6 +10,7 @@ AError
 ARequest
 ASED
 AServer
+AStarlette
 Autogen
 CAs
 Camry

README.md

@@ -39,8 +39,8 @@ As AI agents become more prevalent, their ability to interoperate is crucial for
 
 - 📚 **Explore the Documentation:** Visit the [Agent2Agent Protocol Documentation Site](https://google.github.io/A2A/) for a complete overview, the full protocol specification, tutorials, and guides.
 - 📝 **View the Specification:** [A2A Protocol Specification](https://google.github.io/A2A/specification/)
+- 🐍 Use the [A2A Python SDK](https://github.com/google/a2a-python)
 - 🎬 Use our [samples](/samples) to see A2A in action
-  - Sample A2A Client/Server ([Python](/samples/python/common), [JS](/samples/js/src))
   - [Multi-Agent Web App](/demo/README.md)
   - CLI ([Python](/samples/python/hosts/cli/README.md), [JS](/samples/js/README.md))
 - 🤖 Use our [sample agents](/samples/python/agents/README.md) to see how to bring A2A to agent frameworks
@@ -53,11 +53,6 @@ As AI agents become more prevalent, their ability to interoperate is crucial for
   - [Marvin](/samples/python/agents/marvin/README.md)
   - [Semantic Kernel](/samples/python/agents/semantickernel/README.md)
   - [AG2 + MCP](/samples/python/agents/ag2/README.md)
-- 📑 Review key topics to understand protocol details
-  - [A2A and MCP](https://google.github.io/A2A/topics/a2a-and-mcp/)
-  - [Agent Discovery](https://google.github.io/A2A/topics/agent-discovery/)
-  - [Enterprise Ready](https://google.github.io/A2A/topics/enterprise-ready/)
-  - [Push Notifications](https://google.github.io/A2A/topics/streaming-and-async/#2-push-notifications-for-disconnected-scenarios)
 
 ## Contributing