(docs) validate keys

docs/my-website/docs/set_keys.md

@@ -124,7 +124,7 @@ response = completion("command-nightly", messages, api_version="2023-02-15")
 
 Check if a user submitted a valid key for the model they're trying to call. 
 
-```
+```python
 key = "bad-key"
 response = check_valid_key(model="gpt-3.5-turbo", api_key=key)
 assert(response == False)
@@ -134,7 +134,7 @@ assert(response == False)
 
 This helper reads the .env and returns a list of supported llms for user
 
-```
+```python
 old_environ = os.environ
 os.environ = {'OPENAI_API_KEY': 'temp'} # mock set only openai key in environ