Update 'README.md'

README.md

@@ -12,6 +12,11 @@ https://gpt-index.readthedocs.io/en/latest/
 To build a simple vector store index:
 
 ```
+
+pip install llama-index
+
+
+
 import os
 os.environ["OPENAI_API_KEY"] = 'YOUR_OPENAI_API_KEY'