{Documentation} Fixing missing entry

Summary: Fixing a missing entry in the documentation on how to generate the python stubs

Reviewed By: PiotrBrzyski

Differential Revision: D85351311

fbshipit-source-id: dd9914ae5492e318d431ff5c357de11845e16d5a

Author: SeaOtocinclus

website/docs-research-tools/projectariatools/advanced-installation.mdx

@@ -139,7 +139,7 @@ python3 -m pip install .
 ```
 
 ## Build `projectaria_tools` Python package from source code with type hinting {#python_from_source_type_hint}
-1.
+1. Install pybind11-stubgen to generate the stub files
 2. Generate Python type hinting with generate_stubs.py script once projectaria_tools package is installed
 3. Install type hinting package for projectaria_tools
 ```bash