docs: improve syntax highlighting in code blocks (#8854)

llama/runner/README.md

@@ -4,18 +4,18 @@
 
 A minimial runner for loading a model and running inference via a http web server.
 
-```
+```shell
 ./runner -model <model binary>
 ```
 
 ### Completion
 
-```
+```shell
 curl -X POST -H "Content-Type: application/json" -d '{"prompt": "hi"}' http://localhost:8080/completion
 ```
 
 ### Embeddings
 
-```
+```shell
 curl -X POST -H "Content-Type: application/json" -d '{"prompt": "turn me into an embedding"}' http://localhost:8080/embedding
 ```