clarify install details in docs (#20032)

Author: logan-markewich

docs/src/content/docs/framework/getting_started/installation.mdx

@@ -25,7 +25,7 @@ This is a starter bundle of packages, containing
 - `llama-index-embeddings-openai`
 - `llama-index-readers-file`
 
-**NOTE:** LlamaIndex may download and store local files for various packages (NLTK, HuggingFace, ...). Use the environment variable "LLAMA_INDEX_CACHE_DIR" to control where these files are saved.
+**NOTE:** `llama-index-core` comes pre-bundled with NLTK and tiktoken files to avoid downloads and network calls at runtime.
 
 ### Important: OpenAI Environment Setup