Update README.md

add instruction to launch ES server while using CodeNav as a library

README.md

@@ -99,6 +99,10 @@ under the [codenav_examples](codenav_examples) directory:
 - [create_code_env.py](codenav_examples%2Fcreate_code_env.py)): Creates a `PythonCodeEnv` object and then executes a given code string in this environemnt
 - [create_prompt.py](codenav_examples%2Fcreate_prompt.py): Creates a custom prompt and instantiates and CodeNav agent with that prompt.
 
+**Note** - You will still need to launch ElasticSearch server before running any of the above. To do so run
+```
+python -m codenav.codenav_run init
+```
 
 ## Elasticsearch & Indexing Gotchas 🤔
 
@@ -134,4 +138,4 @@ This project is licensed under the Apache 2.0 License.
   primaryClass={cs.AI},
   url={https://arxiv.org/abs/2406.12276}, 
 }
-```
+```