Fix code fence in AMQP README (Azure#1859)

Author: heaths

sdk/core/azure_core_amqp/README.md

@@ -8,7 +8,7 @@ This crate is part of a collection of crates: for more information please refer
 
 ## Example
 
-```no_run,rust
+```rust,no_run
 use azure_messaging::*;
 
 #[tokio::main]