llava : add requirements.txt and update README.md (#5428)

* llava: add requirements.txt and update README.md

This commit adds a `requirements.txt` file to the `examples/llava`
directory. This file contains the required Python packages to run the
scripts in the `examples/llava` directory.

The motivation of this to make it easier for users to run the scripts in
`examples/llava`. This will avoid users from having to possibly run into
missing package issues if the packages are not installed on their system.

Signed-off-by: Daniel Bevenius <daniel.bevenius@gmail.com>

* llava: fix typo in llava-surgery.py output

Signed-off-by: Daniel Bevenius <daniel.bevenius@gmail.com>

---------

Signed-off-by: Daniel Bevenius <daniel.bevenius@gmail.com>