Update readme after repo migration (#327)

Author: StephenButtolph

README.md

@@ -1,3 +1,9 @@
+# THIS REPOSITORY HAS MOVED
+
+> **⚠️ WARNING: Do not depend on this repository. It has been deprecated.**
+
+Strevm has been moved to [AvalancheGo](https://github.com/ava-labs/avalanchego/tree/master/vms/saevm). This repository is no longer under active development. To open issues, pull requests, and discussions, do so in [AvalancheGo](https://github.com/ava-labs/avalanchego). For the latest releases, see the [AvalancheGo release page](https://github.com/ava-labs/avalanchego/releases). 
+
 # strevm
 
 `strevm` is the reference implementation of Streaming Asynchronous Execution (SAE) of EVM blocks, as described in [ACP-194](https://github.com/avalanche-foundation/ACPs/tree/main/ACPs/194-streaming-asynchronous-execution).